Exposure apparatus and exposure method capable of controlling illumination distribution

ABSTRACT

An exposure apparatus radiates an exposure light beam from an exposure light source onto a reticle via an illumination optical system including a first fly&#39;s eye lens, a second fly&#39;s eye lens, a lens system, a blind, and a condenser lens system, and it projects an image of a pattern on the reticle onto a wafer via a projection optical system. An illumination characteristic is measured by using an evaluation mark plate on a reticle stage and a spatial image-measuring system provided for a wafer stage. The states of the second fly&#39;s eye lens and the lens system are adjusted by the aid of a driving unit on the basis of the measured value. A concentration filter plate, which is formed with a pattern of a predetermined transmittance distribution, is rotatably arranged in the vicinity of a conjugate plane with respect to an image plane between the second lens system and the blind. The angle of rotation of the concentration filter plate 51 is controlled so that the uneven illuminance is corrected. The illumination optical system can be adjusted correctly for a short period of time. It is possible to improve the uniformity of the exposure amount distribution.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an exposure apparatus and anexposure method to be used in order to transfer a mask pattern onto asubstrate through a projection optical system in the lithography stepfor producing, for example, semiconductor elements, liquid crystaldisplacement elements, plasma display elements, or thin film magneticheads. In particular, the present invention relates to an exposureapparatus and an exposure method capable of controlling the distributionof illumination generated by an illumination system automatically orprecisely.

[0003] 2. Description of the Related Art

[0004] In order to respond to the improvement in the degree ofintegration and the degree of fineness of the semiconductor device, theexposure apparatus, which is in charge of the lithography step(representatively including the resist application step, the exposurestep, and the resist development step) for producing the semiconductordevice, is required to further enhance, for example, the resolving powerand the transfer faithfulness. In order to enhance the resolving powerand the transfer faithfulness as described above, it is necessary thatthe wavelength of the exposure light beam as the exposure beam isshortened, the projection optical system having a large numericalaperture is used, and the exposure amount is controlled highlyaccurately in order to expose, with a proper exposure amount, thephotoresist applied on the wafer as the substrate. In order to extractthe image formation characteristic of the projection optical system tothe limit so that the exposure amount is controlled for the photoresisthighly accurately, it is necessary to optimize the illumination opticalsystem so as to enhance the illumination characteristic of theillumination optical system for illuminating the reticle as the maskwith the exposure light beam as far as possible.

[0005] The adjustment to optimize the illumination optical system of theexposure apparatus has been hitherto performed in accordance with thefollowing steps.

[0006] (a) An operator measures the illumination characteristic (forexample, uneven illuminance) of an adjustment objective of theillumination optical system.

[0007] (b) The state (for example, position or angle of inclination) ofa predetermined optical member is adjusted by using a driving unitcorresponding to the illumination characteristic on the basis of theobtained result of the measurement. The driving amount concerning thisprocess is set so that the illumination characteristic is improved asfar as possible by correcting the optical design value on the basis ofthe experience of the operator.

[0008] (c) After the adjustment, the remaining amount of theillumination characteristic is measured again. If the remaining amountexceeds an allowable range, the adjustment is performed again by the aidof the driving unit.

[0009] (d) After the completion of the adjustment, the final state(optimum state) of the optical member is stored.

[0010] The adjustment steps as described above are repeated for everyillumination characteristic of the adjustment objective for each of aplurality of illumination conditions to store the optimum state of thecorresponding optical member. When the illumination condition isswitched, the corresponding optical member is set to be in the optimumstate respectively.

[0011] As described above, the adjustment for optimizing theillumination optical system of the conventional exposure apparatus hasbeen performed by the operator, for example, when the exposure apparatusis assembled and adjusted and when the maintenance is performed.

[0012] However, when the operator performs the adjustment, aninconvenience arises such that a long period of time is required toperform the adjustment. Further, it is necessary to adjust theillumination optical system for each of the plurality of illuminationconditions. Therefore, the overall adjustment time is fairly prolonged.The time required for the optimization is also affected by the degree ofskill of the operator. Therefore, there has been also such a fear thatthe adjustment time is further prolonged depending on the operator.

[0013] When the states of a plurality of optical members in theillumination optical system are required to be adjusted, it is necessaryto consider, for example, the mutual influence caused by the adjustmentas well. Therefore, the adjustment steps have been extremelycomplicated.

[0014] As described above, the adjustment for the conventionalillumination optical system has required the complicated steps whichtake a long period of time. Therefore, for example, it has beendifficult to perform such an operation that the allowable level of apredetermined illumination characteristic is changed depending on, forexample, the required accuracy for the device to be produced. Further,for example, the uneven illuminance of the illumination characteristicis changed in a time-dependent manner, for example, due to thecloudiness of the optical member in the illumination optical system andthe deterioration of the saltpeter material in some cases. However, insuch a case, it has been difficult for the conventional adjustmentmethod to make quick response.

[0015] The uneven illuminance is principally divided into the unevenilluminance which is axially symmetrical with respect to the opticalaxis (centro-symmetrical unevenness), i.e., the quadratic function-likeunevenness, and the inclination unevenness in which the illuminance isgradually increased or decreased in the area across the optical axis,i.e., the linear function-like unevenness. It is necessary that theuneven illuminance as described above is corrected highly accurately inthe orthogonal two directions in the case of the full field exposuretype exposure apparatus such as the stepper. On the other hand, in thecase of the scanning exposure type exposure apparatus such as thosebased on the step-and-scan system, the uneven illuminance in thescanning direction is averaged by the scanning exposure operation tosuch an extent that little problem occurs. Therefore, it is required toespecially correct the uneven illuminance in the non-scanning directionperpendicular to the scanning direction highly accurately.

[0016] The uneven illuminance has been hitherto corrected in ordinarycases by driving a group of predetermined lenses in the illuminationoptical system in the optical axis direction, or by driving the group oflenses so that the tilt angle about the two axes is changed. In general,the situation of the uneven illuminance differs depending on theillumination condition. Especially, in the case of thecentro-symmetrical unevenness, the degree of concaveness/convexness ofthe illuminance is changed corresponding to the change of the positionthrough which the light flux passes in the lens group depending on thenumerical aperture of the exposure light beam (illumination light beam).Therefore, for example, as for the lens group as the adjustmentobjective, the optimum position is previously stored for each of theillumination conditions, and the lens group is driven to the optimumposition every time when the illumination condition is changed.

[0017] A phenomenon is known, in which the cloudy substance adheres tothe surface of the optical element when the exposure light beam in theultraviolet region reacts with a minute amount of organic mattercontained in the gas existing around the optical element. Usually, thegas, from which the organic matter or the like is removed, for example,through a chemical filter, is supplied to the surroundings of therespective lenses of the illumination optical system and the projectionoptical system. However, when the exposure apparatus is used for a longperiod of time, then a slight amount of remaining organic mattergradually increases the cloudiness of the lens, and thecentro-symmetrical unevenness, in which the illuminance is loweredespecially at the central portion, is sometimes advanced in atime-dependent manner. In such a case, the operator has adjusted theposition of the corresponding lens group again, depending on the degreeof advance of the centro-symmetrical unevenness. Further, for example,when the centro-symmetrical unevenness is extremely advanced during theprocess of the use of the exposure apparatus for several years, the lensgroup as the adjustment objective itself is exchanged with a lens grouphaving a strong effect of correction in some cases.

[0018] As described above, the uneven illuminance of the conventionalexposure apparatus has been corrected by controlling the tilt angle orthe position of the predetermined lens group including the lens having acertain curvature (refractive power) in the optical system, or byexchanging the lens group with another lens group.

[0019] However, when it is intended to correct the uneven illuminance bydriving the lens having a certain curvature other than the flat plane,the uniformity of the coherence factor (σ value) of the illuminationlight beam is occasionally deteriorated in the illumination area on thereticle as the mask, and in the exposure area on the wafer as thesubstrate to be exposed. When the uniformity of the σ value isdeteriorated in the exposure area as described above, an inconveniencearises such that the line width uniformity, which is the original objectof the suppression of the uneven illuminance, is lowered. On the otherhand, if the correction amount of the uneven illuminance is set so thatthe deterioration of the uniformity of the σ value is suppressed, alimit appears in the line width control accuracy.

[0020] Especially, in recent years, the design rule (standard linewidth) of the semiconductor device becomes finer and finer year by year.In order to further improve the line width control accuracy, it isdemanded to develop an exposure method which makes it possible toimprove the uniformity of the exposure amount distribution withoutdeteriorating the uniformity of the σ value.

[0021] Taking the foregoing viewpoints into consideration, a firstobject of the present invention is to provide an exposure apparatuswhich makes it possible to correctly adjust an illumination opticalsystem for a short period of time.

[0022] Further, a second object of the present invention is to providean exposure apparatus which makes it possible to substantiallyautomatically adjust an illumination optical system which is capable ofmaking switch to a plurality of illumination conditions.

[0023] Further, a third object of the present invention is to provide amethod for efficiently using such an exposure apparatus and a method forproducing a highly accurate device based on the use of such an exposureapparatus.

[0024] A fourth object of the present invention is to provide anexposure method which makes it possible to improve the uniformity of theexposure amount distribution without substantially deteriorating theuniformity of the coherence factor of an exposure light beam.

[0025] A fifth object of the present invention is to provide an exposureapparatus which makes it possible to carry out the exposure methodprovided in accordance with the fourth object.

[0026] A sixth object of the present invention is to provide a methodfor producing a device, which makes it possible to produce the devicewith a high line width control accuracy by using the exposure methodaccording to the present invention.

SUMMARY OF THE INVENTION

[0027] According to a first aspect of the present invention, there isprovided an exposure apparatus for exposing a second object with anexposure light beam via a first object, the exposure apparatuscomprising: an illumination system which is provided with an opticalmember and which illuminates the first object with the exposure lightbeam; an illumination condition-switching system which is arranged inthe illumination system and which switches an illumination condition ofthe first object with the exposure light beam; and

[0028] an adjusting system which adjusts a state of the optical memberin the illumination system in order to control an illuminationcharacteristic of the illumination system depending on the switchedillumination condition.

[0029] According to the present invention as described above, when theillumination condition is switched with the illuminationcondition-switching system, the state of the optical member (forexample, position in the optical axis direction, position in thedirection perpendicular to the optical axis, and tilt angle) is adjustedby the aid of the adjusting system depending on the illuminationcondition after the switching operation. Accordingly, the predeterminedillumination characteristic of the illumination system can besubstantially automatically controlled to be in a desired state for aplurality of illumination conditions respectively. The adjusting systemmay include a driving system which moves the optical member, and acontrol system which controls the driving system depending on theswitched illumination condition.

[0030] In this arrangement, an example of the predetermined illuminationcharacteristic of the evaluation object is at least one of unevenilluminance of the exposure light beam and a collapse amount of atelecentric property (telecentricity) of the exposure light beam. Bothof them are extremely important characteristics to obtain a highresolution on the second object. Further, it is desirable that theillumination characteristic of the evaluation objective includes aninclination component and a concave/convex component of the unevenilluminance of the exposure light beam, and inclination components(two-dimensional vector amounts) and a magnification component of thecollapse amount of the telecentric property of the exposure light. Thefive components of the illumination characteristic can be easilycontrolled substantially singly by mutually independently driving aplurality of optical members in the illumination system. Therefore, itis especially easy to effect the automatization.

[0031] It is desirable that the exposure apparatus further comprises acharacteristic-measuring system which measures the illuminationcharacteristic of the illumination system, wherein the control systemdetermines and stores a relationship between a driving amount of thedriving system and an amount of change of the illuminationcharacteristic on the basis of a result of the measurement performed bythe characteristic-measuring system. When the illuminationcharacteristic is changed in a time-dependent manner, the illuminationcharacteristic can be quickly restored to a desired state, for example,by periodically measuring the illumination characteristic with thecharacteristic-measuring system, by updating the previously storedrelationship by means of calculation (simulation), or by simultaneouslyusing both of the foregoing means (i.e., by updating the relationship bymeans of calculation during the periodic measurement of the illuminationcharacteristic) so that the optical member is driven on the basis of theobtained result.

[0032] According to a second aspect of the present invention, there isprovided an exposure apparatus for exposing a second object with anexposure light beam via a first object, the exposure apparatuscomprising:

[0033] an illumination system which is provided with an optical memberand which illuminates the first object with the exposure light beam;

[0034] a characteristic-measuring system which measures an illuminationcharacteristic of the illumination system; and

[0035] an adjusting system which adjusts a state of the optical memberin accordance with a result of the measurement performed by thecharacteristic-measuring system.

[0036] According to the exposure apparatus as described above, theillumination system can be correctly adjusted for a short period of timeby driving the adjusting system on the basis of the result of themeasurement performed by the characteristic-measuring system providedwith, for example, a spatial image-measuring system.

[0037] In the present invention as described above, when theillumination system includes an optical integrator (uniformizer orhomogenizer) and a first optical system and a second optical systemwhich introduce the exposure light beam passed through the opticalintegrator into an irradiation plane of the first object or a planeconjugate therewith, the following illumination characteristics can becontrolled substantially mutually independently by performing theadjustment for the states of the foregoing optical members respectivelyas follows:

[0038] (a1) adjustment for the position of the optical integrator in theoptical axis direction: magnification component of the collapse amountof the telecentric property of the exposure light beam;

[0039] (b1) adjustment for the position of the first optical system inthe optical axis direction: concave/convex component of the unevenilluminance;

[0040] (c1) adjustment for the two-dimensional position of the secondoptical system in the direction perpendicular to the optical axis:inclination component of the collapse amount of the telecentric property(two-dimensional vector amount); and

[0041] (d1) adjustment for the tilt angle of the second optical system:inclination component of the uneven illuminance in the tiltingdirection. It is desirable that the tilting angle corresponds to thenon-scanning direction perpendicular to the scanning direction in thecase of the exposure apparatus based on the scanning exposure system,because of the following reason. That is, the uneven illuminance isaveraged owing to the integral effect in the scanning direction, whileit is desirable to make the correction with the tilt, because noaveraging effect is generated in the non-scanning direction.

[0042] In the present invention described above, it is desirable thatthe illumination system further includes an optical element which setsan illuminance distribution of the exposure light beam to a local areafor modified illumination, a beam-shaping optical system whichintroduces the exposure light beam from an exposure light source intothe optical element, a light-collecting optical system which introducesthe exposure light beam from the optical element, and the opticalintegrator which uniformizes the illuminance distribution of theexposure light beam from the light-collecting optical system, whereinthe adjusting system adjusts the state of the light-collecting opticalsystem or the beam-shaping optical system.

[0043] In this arrangement, for example, the beam-shaping optical systemis adjusted so that the magnitude of the illuminance of the exposurelight beam and magnitude of the dispersion of the illuminancedistribution of the exposure light beam are balanced. Thus, it ispossible to decrease the uneven illuminance on condition that the lossof the exposure light beam is minimized.

[0044] According to a third aspect of the present invention, there isprovided an exposure apparatus for exposing a second object with anexposure light beam via a first object, the exposure apparatuscomprising:

[0045] an illumination system which illuminates the first object withthe exposure light beam;

[0046] a characteristic-measuring system which measures an illuminationcharacteristic of the illumination system; and

[0047] a control system which independently determines a magnificationcomponent and an inclination component of a collapse amount of atelecentric property of the exposure light beam from the illuminationcharacteristic measured by the characteristic-measuring system. It iseasy to perform the adjustment substantially mutually independently bydividing the collapse amount of the telecentric property into theinclination component and the magnification component as describedabove. The control system may independently determine a concave/convexcomponent and an inclination component of uneven illuminance of theexposure light beam afforded by the illumination system, from theillumination characteristic measured by the characteristic-measuringsystem.

[0048] According to a fourth aspect of the present invention, there isprovided an exposure method for exposing a second object with anexposure light beam from an illumination, system via a first object, theexposure method comprising the steps of:

[0049] illuminating the first object with the exposure light beam;

[0050] measuring an illumination characteristic of the illuminationsystem;

[0051] independently determining a magnification component and aninclination component of a collapse amount of a telecentric property ofthe exposure light beam from the measured illumination characteristic;

[0052] adjusting the illumination system on the basis of the determinedmagnification and the inclination components of the collapse amount ofthe telecentric property; and

[0053] exposing the second object with the exposure light beam from theadjusted illumination system passing through the first object. Accordingto this exposure method, the telecentric property of the illuminationsystem can be adjusted easily for a short period of time. Thus, it ispossible to improve the throughput. This method may further comprise thestep of independently determining a concave/convex component and aninclination component of uneven illuminance of the exposure light beamafforded by the illumination system from the measured illuminationcharacteristic.

[0054] According to a fifth aspect of the present invention, there isprovided a method for adjusting an exposure apparatus provided with anillumination system for illuminating a first object with an exposurelight beam, for exposing a second object with the exposure light beamvia the first object, the method comprising the steps of:

[0055] setting a predetermined optical member in the illumination systemin a plurality of states to measure an illumination characteristic ofthe illumination system in each state;

[0056] determining a relationship between an amount of change of thestate of the optical member and an amount of change of the illuminationcharacteristic on the basis of a result of the measurement of theillumination characteristic; and

[0057] adjusting the state of the optical member in order to control theillumination characteristic on the basis of the determined relationship.According to this adjusting method, it is possible to efficiently adjustthe illumination characteristic by previously determining therelationship between the driving amount of the optical member and theamount of change of the illumination characteristic. The method mayfurther comprise the step of storing the determined relationship.

[0058] According to a sixth aspect of the present invention, there isprovided an exposure method for exposing a second object with anexposure light beam via a first object, the exposure method comprisingthe steps of:

[0059] radiating the exposure light beam onto the first object; and

[0060] controlling a transmittance distribution of the exposure lightbeam in a planer area traversing an optical axis of the exposure lightbeam in the vicinity of an exposure plane of the second object or in thevicinity of a plane conjugate with the exposure plane.

[0061] According to the exposure method as described above, the unevenilluminance is adjusted not by driving an optical element having apredetermined curvature other than the flat plane. The transmittancedistribution of the planer area is controlled (especially controlledtwo-dimensionally) so that the uneven illuminance is corrected.Accordingly, the illuminance distribution can be controlled withoutsubstantially deteriorating the uniformity of the coherence factor ofthe exposure light beam in the exposure area of the second object.Therefore, the illuminance distribution is controlled so that theunevenness of the cumulative exposure amount on the second object iscorrected, and thus it is possible to improve the uniformity of theexposure amount distribution so that the line width uniformity may bereliably improved. Further, the transmittance distribution is not fixed,it can be controlled variably two-dimensionally. Therefore, when anycloudiness or the like appears on the optical element such as those ofthe illumination system, and the illuminance distribution on the secondobject is changed in a time-dependent manner, then the transmittancedistribution is controlled so that the change is offset. Thus, it ispossible to always maintain high uniformity of the exposure amountdistribution.

[0062] In this process, for example, the transmittance distribution forthe exposure light beam is controlled to give a concentric distributionabout the center of the optical axis so that the unevenness of theexposure amount distribution for the second object is corrected. Whenthe concentric distribution is given as described above, it is possibleto appropriately correct the uneven illuminance (centro-symmetricalunevenness) which is axially symmetrical with respect to the opticalaxis. Further, the centro-symmetrical unevenness can be correctedsubstantially continuously within a predetermined range by rotating thetransmittance distribution.

[0063] In another example, the transmittance distribution for theexposure light beam is controlled to give a predetermined distributionin a first direction so that the unevenness of the exposure amountdistribution for the second object is corrected. That is, thetransmittance distribution is controlled to give a one-dimensionalpredetermined distribution. The direction of the one-dimensionaldistribution is variable. When the one-dimensional transmittancedistribution is used as described above, it is possible to correct theunevenness of the cumulative exposure amount in the non-scanningdirection (direction perpendicular to the scanning direction) when thescanning exposure is performed. That is, when the predetermineddistribution is a distribution which changes one-dimensionallysymmetrically about the center of the optical axis, thecentro-symmetrical unevenness (quadratic function-like unevenness) canbe corrected substantially continuously within a predetermined rangeafter the scanning exposure. When the predetermined distribution is adistribution in which the transmittance is gradually increased ordecreased as the position is separated farther from the optical axis,the inclination unevenness (linear function-like unevenness) can becorrected substantially continuously within a predetermined range afterthe scanning exposure.

[0064] The transmittance distribution for the exposure light beam may befurther controlled in a direction intersecting the direction of thepredetermined distribution with the same distribution as thepredetermined distribution or with another distribution. When aplurality of one-dimensional transmittance distributions are combined,it is possible to correct the two-dimensional uneven illuminance such asthe inclination unevenness and the centro-symmetrical unevenness in thestationary state. The present invention can be also applied to theexposure apparatus of the full filed exposure type such as the stepper.It is also possible to omit the mechanism for driving a large lens groupto be used to correct the uneven illuminance.

[0065] In the scanning exposure system in which the first object and thesecond object are synchronously moved in a scanning direction when thesecond object is exposed, it is desirable that the transmittancedistribution for the exposure light beam is controlled so that exposureamount distribution (exposure amount distribution in the non-scanningdirection), which is obtained by adding up an exposure amount of theexposure light beam for the second object in the scanning direction, isuniformized. In this process, the uneven illuminance in the scanningdirection is averaged by the scanning exposure. Therefore, thecumulative exposure amount distribution is uniformized on the entiresurface of the second object by uniformizing the exposure amountdistribution in the non-scanning direction perpendicular to the scanningdirection. Thus, it is possible to obtain a high line width controlaccuracy.

[0066] According to a seventh aspect of the present invention, there isprovided an exposure apparatus for exposing a second object with anexposure light beam via a first object, the exposure apparatuscomprising:

[0067] an illumination system which illuminates the first object withthe exposure light beam; and

[0068] at least one filter which is arranged in the vicinity of anexposure plane of the second object or in the vicinity of a planeconjugate with the exposure plane on an optical path for the exposurelight beam up to the second object and which has a predeterminedtransmittance distribution with respect to the exposure light beam.

[0069] According to the present invention as described above, thetransmittance distribution can be controlled substantially continuously,for example, by mechanically rotating the filter, or by electricallyrotating the transmittance distribution of the filter. Therefore, it ispossible to carry out the exposure method according to the sixth aspectof the present invention. In this arrangement, the apparatus may furthercomprise a driving unit which controls an angle of rotation of thefilter itself or which makes control to electrically rotate thetransmittance distribution of the filter. Accordingly, it is possible toautomatically correct the unevenness of the exposure amount.

[0070] In this arrangement, the illumination system may include onestage of optical integrator or a plurality of stages of opticalintegrators for uniformizing an illuminance distribution of the exposurelight beam, and a field diaphragm for defining an illumination area onthe first object of the exposure light beam from the optical integrator;wherein the filter may be arranged on a plane in the vicinity of thefield diaphragm or on a plane in the vicinity of an irradiation plane ofthe first object. Accordingly, the filter can be easily arranged.

[0071] The filter may be composed of two sheets of a first filter and asecond filter which have the same transmittance distribution in aone-dimensional direction symmetrically with respect to an optical axisrespectively, and the two sheets of the filters may be rotated inmutually opposite phases. Accordingly, the centro-symmetrical unevennesscan be corrected continuously by means of the simple control. When thepresent invention is applied to an exposure apparatus based on thescanning exposure system, it is desirable that the exposure apparatusfurther comprises a stage system which synchronously moves the firstobject and the second object in a scanning direction; an exposure amountdistribution-measuring unit which measures a distribution of added-upvalue in the scanning direction of an exposure amount of the exposurelight beam on the second object; and a control unit which controls anangle of rotation of the filter by the aid of the driving unit inaccordance with the exposure amount distribution measured by thedistribution-measuring unit. In this arrangement, the unevenness of theexposure amount can be corrected highly accurately by measuring thedistribution of the added-up value in the non-scanning direction withthe distribution-measuring unit, and rotating the filter so that thedistribution is uniform.

[0072] According to an eighth aspect of the present invention, there isprovided an exposure apparatus for illuminating a first object with anexposure light beam and exposing a second object with the exposure lightbeam via the first object, the exposure apparatus comprising:

[0073] an illumination optical system which is capable of illuminatingthe first object under a plurality of illumination conditionsrespectively and in which an illuminance distribution of the exposurelight beam has an identical tendency for the plurality of illuminationconditions respectively; and

[0074] an optical member which is arranged on an optical path for theexposure light beam up to the second object and which adjusts theilluminance distribution.

[0075] According to the exposure apparatus of the present invention asdescribed above, when the illumination condition is changed, forexample, from the ordinary illumination to the modified illumination orthe small a value illumination, the uniformity of the exposure amountdistribution can be improved by offsetting the amount of change of theuneven illuminance by means of the optical member, for example, when thedegree of the centro-symmetrical unevenness or the inclinationunevenness is slightly changed.

[0076] In this arrangement, it is desirable that the illuminationoptical system is adjusted to have uneven illuminance in which theilluminance distribution is substantially symmetrical with respect to anoptical axis of the illumination optical system. Accordingly, it is easyto correct the uneven illuminance. For example, the optical memberincludes at least one optical fiber which is arranged separately from anexposure plane of the second object or a conjugate plane thereof andwhich has a predetermined transmittance distribution with respect to theexposure light beam.

[0077] According to an ninth aspect of the invention, an exposure methodfor illuminating a first object with an exposure light beam and exposinga second object with the exposure light beam via the first object isprovided. The exposure method comprises:

[0078] changing an illumination condition for the first object dependingon a pattern to be transferred onto the second object;

[0079] adjusting an inclination component and a centro-symmetricalcomponent of uneven illuminance or uneven exposure amount in anirradiation area of the exposure light beam, respectively; and

[0080] adjusting the centro-symmetrical component without adjusting theinclination component during a predetermined period after the adjustmentof the uneven illuminance or uneven exposure amount.

[0081] According to an tenth aspect of the invention, an exposure methodfor irradiating a first object with an exposure light beam via anillumination optical system and exposing a second object with theexposure light beam via the first object is provided. The exposuremethod comprises:

[0082] detecting the exposure light beam on a predetermined plane onwhich the second object is arranged to measure an illuminationcharacteristic including at least one of a distribution of exposureamount or illuminance in an irradiation area of the exposure light beamand a telecentricity of the illumination optical system;

[0083] moving at least one optical element of the illumination opticalsystem on the basis of the measured illumination characteristic;

[0084] updating the measured illumination characteristic by means ofcalculation until the illumination characteristic is measured next time;and

[0085] moving the at least one optical element on the basis of theupdated illumination characteristic.

[0086] A method for producing a device according to the presentinvention comprises the step of transferring a device pattern onto asubstrate by using the exposure method according to any one of theaspects of the present invention. According to the present invention, itis possible to mass-produce a highly functional device with a high linewidth control accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

[0087]FIG. 1 shows, with partial cutout, a front view illustrating aprojection exposure apparatus according to a first embodiment of thepresent invention.

[0088]FIG. 2 shows a perspective view illustrating an illumination area35 and an optical system ranging from a second fly's eye lens 9 to asecond lens system 13 shown in FIG. 1.

[0089]FIG. 3A shows a plan view illustrating a reticle stage 31 and anevaluation mark plate 33, and FIG. 3B shows a magnified plan view toillustrate a method for detecting an image 36AP of an evaluating mark.

[0090]FIGS. 4A-4C illustrate a method for measuring an inclinationcomponent and a concave/convex component of uneven illuminance.

[0091]FIGS. 5A-5F illustrates a method for measuring an inclinationcomponent and a magnification component of illumination telecentricity.

[0092]FIG. 6A shows, with partial cutout, main components to be usedwhen the modified illumination is performed by an illumination opticalsystem ILS shown in FIG. 1, and FIG. 6B shows a front view illustratingan aperture diaphragm plate 10 shown in FIG. 6A.

[0093]FIG. 7 shows an example of the relationship between the magnitudeof illuminance and the uneven illuminance when the modified illuminationis performed.

[0094]FIG. 8 shows a flow chart illustrating an example of a measurementsequence for the driving rate of the entire driving unit in theillumination optical system.

[0095]FIG. 9 shows a flow chart illustrating an example of an automaticadjustment sequence for the illumination optical system.

[0096]FIG. 10 shows a flow chart illustrating an example of anadjustment sequence for the modified illumination according to a secondembodiment.

[0097]FIG. 11 shows, with partial cutout, an arrangement illustrating aprojection exposure apparatus according to a third embodiment of thepresent invention.

[0098]FIG. 12 shows a perspective view illustrating the relationshipconcerning an illumination area 35 and an optical system ranging from asecond fly's eye lens 9 to a fixed blind 14A shown in FIG. 11.

[0099]FIG. 13A shows a plan view illustrating an exposure area and anuneven illuminance sensor 42, and FIG. 13B shows an example of adetection signal obtained by the uneven illuminance sensor 42.

[0100]FIGS. 14A-14C show states in which the angle of rotation of aconcentration filter plate 51 is changed in three ways in the thirdembodiment.

[0101]FIGS. 15A-15C show the concentration filter plate 51 and filterplates equivalent thereto.

[0102]FIG. 16 shows a perspective view illustrating the relationshipconcerning an illumination area 35 and an optical system ranging from asecond fly's eye lens 9 to a fixed blind 14A of a projection exposureapparatus according to a fourth embodiment of the present invention.

[0103]FIG. 17A shows a concentration filter plate 51A of the fourthembodiment, FIG. 17B shows a transmittance distribution of theconcentration filter plate 51A, FIG. 17C shows a second concentrationfilter plate 51B of the second embodiment, FIG. 17D shows atransmittance distribution of the concentration filter plate 51B, andFIG. 17E shows a final transmittance distribution.

[0104]FIGS. 18A-18C show states in which the angle of rotation of aconcentration filter plate 155 according to a fifth embodiment of thepresent invention is changed in three ways.

[0105]FIG. 19A shows a first concentration filter plate 161 according toa sixth embodiment of the present invention, and FIG. 19B showstransmittance distributions at a variety of angles of rotation of theconcentration filter plate 161.

[0106]FIG. 20A shows a second concentration filter plate 63 according tothe sixth embodiment, and FIG. 20B shows transmittance (T(r))distributions at a variety of angles of rotation of the concentrationfilter plate 63.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0107] An exemplary embodiment of the present invention will beexplained below with reference to the drawings. In this embodiment, thepresent invention is applied to a scanning exposure type projectionexposure apparatus based on the step-and-scan system or thestep-and-stitch system.

First Embodiment

[0108]FIG. 1 shows a schematic arrangement of a projection exposureapparatus of this embodiment. In FIG. 1, an ArF excimer laser lightsource (wavelength: 193 nm) is used as an exposure light source 1.However, those usable as the exposure light source 1 include, forexample, a KrF excimer laser (wavelength: 248 nm), an F₂ laser(wavelength: 157 nm), a Kr₂ laser (wavelength: 146 nm), a high harmonicwave generator of YAG laser, a high harmonic wave generator ofsemiconductor laser, and a mercury lamp. An exposure light beam IL(exposure beam), which is composed of an ultraviolet pulse light beamhaving a wavelength of 193 nm radiated from the exposure light source 1,passes through a beam matching unit (BMU) 2 for positionally matchingthe optical path with respect to the main exposure apparatus body, andit comes into a variable light-reducing unit 3 to serve as a lightattenuator. An exposure control unit 21, which is provided to controlthe exposure amount with respect to the photoresist on a wafer, controlsthe start and the stop of the light emission of the exposure lightsource 1 as well as the output (oscillation frequency and pulse energy).The dimming ratio for the variable light-reducing unit 3 is adjustedcontinuously or in a stepwise manner.

[0109] The exposure light beam IL, which has passed through the variablelight-reducing unit 3, passes through a beam-shaping system 5 composedof a first lens system 4A and a second lens system 4B arranged along apredetermined optical axis, and it comes into a first fly's eye lens 6to serve as a first stage optical integrator (uniformizer orhomogenizer). The exposure light beam IL, which outgoes from the firstfly's eye lens 6, comes into a second fly's eye lens 9 to serve as asecond stage optical integrator via a first lens system 7A, an opticalpath-bending mirror 8, and a second lens system 7B. A relay opticalsystem (or may be referred to as “beam-shaping system” as well), whichserves as a light-collecting optical system, is constructed by the firstlens system. 7A and the second lens system 7B.

[0110] An aperture diaphragm plate 10 is arranged rotatably by the aidof a driving motor 10 e at a light-outgoing plane of the second fly'seye lens 9, i.e., an optical Fourier transformation plane (pupil planeof the illumination system) with respect to the pattern plane (reticleplane) of a reticle 28 as the exposure objective. As shown in a frontview of FIG. 6B, the aperture diaphragm plate 10 is exchangeablyarranged with a circular aperture diaphragm 10 a for the ordinaryillumination, an aperture diaphragm 10 b for zonal illumination as anexample of the modified illumination, an aperture diaphragm 10 ccomposed of a plurality of (in this embodiment, four) eccentric smallapertures for modified light source (or so-called oblique illumination)as another example of the modified illumination, and a small circularaperture diaphragm 10 d for the small coherence factor (σ value). Theaperture diaphragm 10 c may be also referred to as the aperturediaphragm for the four-spot illumination. The “illuminationcondition-switching system” for switching the illumination conditioninto any one of the plurality of illumination conditions (ordinaryillumination, modified illumination, and small σ value illumination) isconstructed by the aperture diaphragm plate 10 and the driving motor 10e. The main control system 22, which collectively manages and controlsthe operation of the entire apparatus, sets the illumination conditionby the aid of the driving motor 10 e.

[0111] With reference to FIG. 1, the aperture diaphragm 10 a for theordinary illumination is installed at the light-outgoing plane of thesecond fly's eye lens 9. The exposure light beam IL, which outgoes fromthe second fly's eye lens 9 and which has passed through the aperturediaphragm 10 a, comes into a beam splitter 11 having a hightransmittance and having a low reflectance. The exposure light beam,which is reflected by the beam splitter 11, comes into an integratorsensor 20 composed of a photoelectric detector via a light-collectinglens 19. A detection signal S1 of the integrator sensor 20 is suppliedto an exposure control unit 21. The relationship between the detectionsignal of the integrator sensor 20 and the illuminance of the exposurelight beam IL on the wafer W as the substrate to be exposed ispreviously measured highly accurately, and it is stored in a memory inthe exposure control unit 21. The exposure control unit 21 isconstructed so that the illuminance (average value) of the exposurelight beam IL with respect to the wafer W and the integral value thereofmay be indirectly monitored in accordance with the detection signal ofthe integrator sensor 20.

[0112] The exposure light beam IL, which is transmitted through the beamsplitter 11, passes along the optical axis IAX through a first lenssystem 12 (first optical system) and a second lens system 13 (secondoptical system), and it successively comes into a fixed blind(illumination field diaphragm which has an opening for defining theexposure area 35P on the wafer W (projection area which is conjugatewith the illumination area 35 in relation to the projection opticalsystem PL and onto which the image of the pattern in the illuminationarea 35 is formed) and the illumination area 35 on the reticle 28irradiated with the exposure light beam IL and which has a width of theopening fixed in relation to at least the scanning direction of thescanning direction (Y direction) in which the reticle 28 and the wafer Ware moved during the scanning exposure and the non-scanning direction (Xdirection) perpendicular to the scanning direction in this embodiment)14A and a movable blind (movable illumination field diaphragm) 14B. Thelatter movable blind 14B is installed at the conjugate plane withrespect to the reticle plane. The former fixed blind 14A is arranged ata plane which is defocused by a predetermined amount from the conjugateplane. For example, as disclosed in Japanese Laid-Open PatentPublication No. 4-196513, the fixed blind 14A has an opening which isarranged to extend in a linear slit configuration or in a rectangularconfiguration (hereinafter collectively referred to as “slit-shapedconfiguration”) in the non-scanning direction substantially about thecenter of the optical axis AX in a circular field of the projectionoptical system PL. In order to avoid any unnecessary exposure upon thestart and the end of the scanning exposure for the respective shot areason the wafer W, the movable blind 14B is used to vary the width in thescanning direction of the exposure area 35P and the illumination area 35defined by the fixed blind 14A. The movable blind 14B is also used tovary the width corresponding to the size of the pattern area of thereticle 28 concerning the direction (non-scanning direction)perpendicular to the scanning direction SD. The information on theopening ratio of the movable blind 14B is also supplied to the exposurecontrol unit 21. The value, which is obtained by multiply theilluminance determined from the detection signal of the integratorsensor 20 by the opening ratio, is the actual illuminance on the waferW. The arrangement of the fixed blind 14A and the movable blind 14B isnot limited to the arrangement shown in FIG. 1. For example, the fixedblind 14A may be arranged closely to the reticle 28 between the reticle28 and the illumination optical system.

[0113] The exposure light beam IL, which has passed through the fixedblind 14A during the exposure, radiates the illumination area(illumination field area) 35 on the pattern plane (lower surface) of thereticle 28 as the mask via an optical path-bending mirror 15, animage-forming lens system 16, a sub-condenser lens system 17, and a maincondenser lens system 18. Under the illumination light beam IL, theimage of the circuit pattern in the illumination area of the reticle 28is transferred to the slit-shaped exposure area 35P of the photoresistlayer on the wafer W as the substrate (substrate to be exposed) arrangedat the image formation plane of the projection optical system PL at apredetermined projection magnification β (β is, for example ¼, ⅕) viathe projection optical system PL which is telecentric on the both sides.The reticle 28 and the wafer W correspond to the first object and thesecond object of the present invention respectively. The wafer W is, forexample, a disk-shaped substrate of semiconductor (silicon or the like),SOI (silicon on insulator) or the like. The projection optical system PLas the projection system of this embodiment is a dioptric system(refractive system). However, it is needless to say that thecata-dioptric system (reflecting refractive system) and the reflectivesystem can be also used. The following description will be made assumingthat the Z axis extends in parallel to the optical axis AX of theprojection optical system PL, the Y axis extends in the scanningdirection (direction parallel to the plane of paper of FIG. 1 in thisembodiment) in the plane perpendicular to the Z axis, and the X axisextends in the non-scanning direction (direction perpendicular to theplane of paper of FIG. 1 in this embodiment) perpendicular to thescanning direction.

[0114] In FIG. 1, the illumination optical system ILS is constructed,for example, by the exposure light source 1, the beam matching unit 2,the variable light-reducing unit 3, the beam-shaping system 5, the firstfly's eye lens 6, the first lens system 7A, the second lens system 7B,the second fly's eye lens 9, the first lens system 12, the second lenssystem 13, the fixed blind 14A, the movable blind 14B, the image-forminglens system 16, the sub-condenser lens system 17, and the main condenserlens system 18. The illumination optical system ILS or one obtained byadding the exposure light source thereto corresponds to the illuminationsystem of the present invention. The optical axis IAX of theillumination optical system ILS is coincident with the optical axis AXof the projection optical system PL on the reticle 28. In thisembodiment, a first driving unit 23, a second driving unit 24, a drivingunit group 25 are installed to the second fly's eye lens 9, the firstlens system 12, and the second lens system 13 respectively.

[0115]FIG. 2 shows a perspective view illustrating the relationshipbetween the illumination area 35 and the optical system ranging from thesecond fly's eye lens 9 to the second lens system 13 shown in FIG. 1. InFIG. 2, the scanning direction SD (Y direction) for the reticle withrespect to the illumination area 35, and the direction on the secondfly's eye lens 9 corresponding to the non-scanning direction (Xdirection) are the y direction and the x direction respectively. Thefirst driving unit 23 adjusts the position of the second fly's eye lens9 in the direction of the optical axis IAX (direction of the arrow A1).The second driving unit 24 adjusts the position of the first lens system12 in the direction of the optical axis IAX (direction of the arrow A2).The driving unit group 25 shown in FIG. 1 is constructed by a thirddriving unit 25X, a fourth driving unit 25Y, and a fifth driving unit25T shown in FIG. 2. The driving units 25X, 25Y adjust positions of thesecond lens system 13 in the y direction (direction of the arrow A4) andthe x direction (direction of the arrow A3) perpendicular to the opticalaxis IAX of the second lens system 13 respectively. The driving unit 25Tadjusts the tilt angle of the second lens system 13 about the axispassing through the optical axis IAX and parallel to the y axis(direction of the arrow A5). In other words, the driving unit 25Tadjusts the tilt angle (angle of inclination) of the lens system 13 inthe direction corresponding to the non-scanning direction of theillumination area 35.

[0116] Those usable as the driving units 23 to 25T include, for example,a micrometer based on the electric system, and a driving unit fordisplacing a flange section of an optical member as a driving objectivewith a driving element such as a piezoelectric element. In this case,each of the driving units 23 to 25T is incorporated with an encoder (forexample, a rotary encoder) (not shown) to indicate the displacementamount of the optical member within a range capable of driving (drivingstroke). Detection signals from the encoders are supplied to the drivingsystem 26 shown in FIG. 1. The driving system 26 controls the states ofthe second fly's eye lens 9, the first lens system 12, and the secondlens system 13 by the aid of the driving units 23 to 25T on the basis ofthe driving information from the main control system 22 and thedetection signals. Alternatively, for example, an electrostatic capacitysensor may be used for the encoder for the driving unit 23 to 25T.

[0117] In this embodiment, as shown in FIG. 6A, the arrangement is madesuch that when the modified illumination is performed, the first fly'seye lens 6 can be exchanged with an light amount distribution-convertingelement 55 composed of a diffractive optical element (DOE) by using aswitching unit 56. The light amount distribution-converting element 55corresponds to the optical element for setting the exposure light beamto a local area.

[0118] In FIG. 6A, when the modified illumination is performed, forexample, the aperture diaphragm 10 b having the zonal configuration (orthe aperture diaphragm 10 c for the four-spot illumination) is installedat the light-outgoing plane of the second fly's eye lens 9. The lightamount distribution-converting element 55 collects the exposure lightbeam IL to the area having a substantially zonal configuration of thelight-incoming plane of the second fly's eye lens 9 by means of thediffracting effect. The light amount distribution-converting element 55is also included in the illumination optical system ILS. Accordingly,the efficiency of use of the exposure light beam IL is enhanced. A highilluminance is obtained on the wafer even when the modified illuminationis performed. In this process, a driving unit 58 for adjusting theposition of the second lens system 7B in the direction of the opticalaxis IAX, a driving unit 62 for adjusting the position of the first lenssystem 7A in the two-dimensional direction perpendicular to the opticalaxis, and a driving unit 57 for adjusting the position u of the secondlens system 4B of the beam-shaping system 5 in the direction of theoptical axis IAX are used. An encoder is also provided for each of thedriving units 57, 58, 62 composed of, for example, a micrometer based onthe electric system. The arrangement is made such that the drivingsystem 26 is capable of controlling the states of the second lens system57, the second lens system 7B, and the first lens system 7A by the aidof the driving units 57, 58, 62 on the basis of the driving informationof the main control system 22 shown in FIG. 1 and the detection signalsobtained by the encoders. The switching unit 56 may be provided with aplurality of light amount distribution-converting elements forgenerating exposure light beams IL having different illumination areas(intensity distributions) on the light-incoming plane of the secondfly's eye lens 9. The light amount distribution-converting element, withwhich the efficiency of use of the exposure light beam IL is thehighest, is selected to be arranged in the illumination optical pathdepending on the illumination condition (i.e., the intensitydistribution of the exposure light beam IL on the pupil plane of theillumination optical system, or one of the plurality of aperturediaphragms 10 a to 10 d arranged in the illumination optical path inthis embodiment). In this arrangement, it is not necessarilyindispensable to provide the first fly's eye lens 6 for the switchingunit 56.

[0119] With reference to FIG. 1 again, the reticle 28 is attracted andheld on a reticle stage 31. The reticle stage 31 is placed so that it ismovable at a constant velocity in the Y direction on a reticle base 32,and it is finely movable in the X direction, the Y direction, and thedirection of rotation. The two-dimensional position and the angle ofrotation of the reticle stage 31 (reticle 28) are measured in real timeby the aid of laser interferometers in a driving control unit 34. Basedon the result of the measurement and the control information from themain control system 22, a driving motor (for example, a linear motor ora voice coil motor) in the driving control unit 34 controls the scanningvelocity and the position of the reticle stage 31. An evaluation markplate 33 composed of a glass plate is fixed in the vicinity of thereticle 28 on the reticle stage 31.

[0120]FIG. 3A shows a plan view illustrating the reticle stage 31 shownin FIG. 1. In FIG. 3A, the evaluation mark plate 33 is fixed on anopening of an area adjacent to the reticle 28 on the reticle stage 31 inthe scanning direction SD (Y direction). For example, thirteentwo-dimensional identical evaluation marks 36A, 36B, . . . 36M areformed in a substantially uniform distribution in an area havingapproximately the same size as that of the illumination area 35 of theevaluation mark plate 33. The evaluation mark 36A is a two-dimensionalmark obtained by combining an X axis mark 37×composed of aline-and-space pattern arranged at a predetermined pitch in the Xdirection, and a Y axis mark 37Y composed of a line-and-space patternarranged at a predetermined pitch in the Y direction. Alternatively, itis possible to use, for example, a box-in-box mark. In this embodiment,as described later on, when the collapse amount of the telecentricproperty of the illumination optical system is measured, then thereticle stage 31 is driven in the Y direction to allow the center of theevaluation mark plate 33 (center of the evaluation mark 36G) to coincidewith the center of the illumination area 35 (optical axis AX), and theimages of the evaluation marks 36A, 36B, . . . 36M are projected ontothe wafer via the projection optical system PL. The image 36AP of theevaluation mark 36A is shown in a magnified view in FIG. 3B.

[0121] With reference to FIG. 1 again, the wafer W is attracted and heldon a wafer stage 39 by the aid of a wafer holder 38. The wafer stage 39is movable two-dimensionally along the XY plane which is parallel to theimage plane of the projection optical system PL on a wafer base 40. Thatis, the wafer stage 39 is movable at a constant velocity in the Ydirection on the wafer base 40, and it is movable in a stepping mannerin the X direction and in the Y direction. Further, a Z levelingmechanism for controlling the position of the wafer W in the Z direction(focus position) and the angle of rotation about the X axis and the Yaxis is also incorporated into the wafer stage 39. A multiple-pointautofocus sensor (not shown) for measuring the focus position at aplurality of measuring points on the surface of the wafer W is alsoprovided. During the exposure, the Z leveling mechanism is driven inaccordance with the autofocus system on the basis of the measured valueof the autofocus sensor. Accordingly, the surface of the wafer W isfocused on the image plane of the projection optical system PL. When theillumination characteristic is measured, for example, the Z levelingmechanism in the wafer stage 39 is driven on the basis of the measuredvalue of the autofocus sensor. Accordingly, the focus position on theupper surface of the wafer stage 39 can be controlled by an arbitraryamount.

[0122] The positions of the wafer stage 39 in the X direction and the Ydirection and the angles of rotation about the X axis, the Y axis, andthe Z axis are measured in real time by laser interferometers in thedriving control unit 41. Based on the result of the measurement and thecontrol information from the main control system 22, a driving motor(for example, a linear motor) in the driving control unit 41 controlsthe position and the scanning velocity of the wafer stage 39.

[0123] The main control system 22 sends, to the driving control units34, 41, various pieces of information concerning, for example, themovement position, the movement velocity, the rate of acceleration ofthe movement, and the position offset of each of the reticle stage 31and the wafer stage 39. During the scanning exposure, the wafer W isscanned at a velocity of β·Vr (β is the projection magnification fromthe reticle 28 to the wafer W) in the −Y direction (or in the +Ydirection) with respect to the exposure area 35P of the pattern image ofthe reticle 28 by the aid of the wafer stage 39 in synchronization withthe scanning of the reticle 28 at a velocity Vr in the +Y direction (orin the −Y direction) with respect to the illumination area 35 of theexposure light beam IL by the aid of the reticle stage 31. During thisprocess, in order to avoid any exposure for unnecessary portions uponthe start and the end of the scanning exposure, the opening/closingoperation of the movable blind 14B is controlled by the driving controlunit 34.

[0124] Further, the main control system 22 reads, from the exposure datafile, various exposure conditions to perform the scanning exposure in aproper exposure amount for the photoresist in the respective shot areason the wafer W to execute an optimum exposure sequence in combinationwith the exposure control unit 21 as well. That is, when the command tostart the scanning exposure for one shot area on the wafer W is givenfrom the main control system 22 to the exposure control unit 21, thenthe exposure control unit 21 starts the light emission of the exposurelight source 1, and it calculates an integral value of the illuminanceof the exposure light beam IL with respect to the wafer W (sum of thepulse energy per unit time) by the aid of the integrator sensor 20. Theintegral value is reset to zero upon the start of the scanning exposure.The exposure control unit 21 successively calculates the integral valueof the illuminance. Based on the obtained result, the exposure controlunit 21 controls the output of the exposure light source 1 (oscillationfrequency and pulse energy) and the dimming ratio of the variablelight-reducing unit 3 so that the proper exposure amount is obtained atthe respective points of the photoresist on the wafer W after thescanning exposure. When the scanning exposure for the concerning shotarea is completed, the light emission of the exposure light source 1 isstopped.

[0125] An uneven illuminance sensor 42, which is composed of aphotoelectric detector and which has a pin hole-shaped light-receivingsection 42 a (see FIG. 4A), is installed in the vicinity of the waferholder 38 on the wafer stage 39 of this embodiment. A detection signalS2 of the uneven illuminance sensor 42 (exposure amountdistribution-measuring unit) is also supplied to the exposure controlunit 21. The uneven illuminance sensor 42 may be used, for example, witha light-receiving section (corresponding to the light-receiving section42 b shown in FIG. 13A) composed of, for example, a line sensor or a CCDextending in the scanning direction (Y direction) in which the wafer Wis relatively moved with respect to the exposure area 35P during thescanning exposure, in place of or in combination of the pin hole-shapedlight-receiving section 42 a. In this case, illuminances, which aredetected at a plurality of points in the scanning direction in theexposure area 35P respectively, may be added up at respective positionsconcerning the non-scanning direction (X direction) perpendicular to thescanning direction, and the illuminance distribution concerning thenon-scanning direction may be determined on the basis of the added-upvalue. It is possible to obtain the illuminance distribution (unevenilluminance) in the non-scanning direction in consideration of theaveraging effect of the uneven illuminance in the scanning direction bythe scanning exposure, i.e., the exposure amount distribution (exposureamount unevenness) concerning the non-scanning direction on the waferafter the scanning exposure. Therefore, the optimization of theillumination characteristic (correction of the uneven illuminance)described later on may be performed by using the result of themeasurement. The same or equivalent illuminance distribution can be alsodetermined by using the pin hole-shaped light-receiving section 42 a bytwo-dimensionally moving the wafer stage 39 during the measurement ofthe illuminance. Although not shown, a radiation amount monitor, whichhas a light-receiving section to cover the entire exposure area 35P, isalso installed. A coefficient, which is used to indirectly determine theilluminance on the wafer W from the detection signal of the integratorsensor 20, is calculated on the basis of the detection signal of theradiation amount monitor and the detection signal of the integratorsensor 20. Further, a scanning plate 43, which is composed of a glasssubstrate, is installed in the vicinity of the wafer holder 38 on thewafer stage 39. A substantially square opening pattern 43 a is formed ina light-shielding film on the scanning plate 43. A light-collecting lens44 and a photoelectric detector 45 are arranged on the bottom surfaceside of the scanning plate 43 in the wafer stage 39. A spatialimage-measuring system 46 is constructed by the scanning plate 43, thelight-collecting lens 44, and the photoelectric detector 45. A detectionsignal S3 of the photoelectric detector 45 is supplied to a calculatingsection in the exposure control unit 21. Only a part of the spatialimage-measuring system 46 (including, for example, the scanning plate 43and at least a part of the light-feeding system including, for example,the light-collecting lens 44 in this embodiment) may be provided on thewafer stage 39. The remaining constitutive components (for example, thephotoelectric detector 45) may be arranged at the outside of the waferstage 39. As for the spatial image-measuring system 46, only one openingpattern 43 a is formed for the scanning plate 43. When the illuminationcharacteristic is measured as described later on, then the wafer stage39 is subjected to two-dimensional stepping, and the opening pattern 43a is relatively moved in the scanning direction and the non-scanningdirection (X direction and Y direction) respectively with respect to therespective images of the plurality of (thirteen, in this embodiment)evaluation marks arranged in the illumination area 35. For example, theopening patterns 43 a of the same number as that of the plurality ofevaluation marks may be formed on the scanning plate 43. The respectiveimages of the plurality of evaluation marks may be collectively detectedrespectively during the relative movement of the image of the evaluationmark and the opening pattern concerning the scanning direction andduring the relative movement of the image of the evaluation mark and theopening pattern concerning the non-scanning direction. Further, forexample, the opening patterns 43 a of the same number as that of theplurality of (five, in this embodiment) evaluation marks separated inthe non-scanning direction may be formed on the scanning plate 43 in thenon-scanning direction. The wafer stage 39 may be moved in the scanningdirection to continuously detect the images of the respective evaluationmarks arranged in the scanning direction for each of the openingpatterns. Oppositely to the above, the opening patterns 43 a of the samenumber as that of the evaluation marks may be formed on the scanningplate 43 concerning the scanning direction. The wafer stage 39 may bemoved in the non-scanning direction to continuously detect the images ofthe evaluation marks for each of the opening patterns. In thisprocedure, it is preferable that the movable blind 14B is driven inaccordance with the movement of the wafer stage 39 so that only a partof the illumination area 35 is irradiated with the exposure light beamIL during the detection of the plurality of evaluation marks. In theformer, it is necessary that the wafer stage 39 is subjected to thestepping in the scanning direction when the image of the evaluation markand the opening pattern are relatively moved concerning the non-scanningdirection. In the latter, it is necessary that the wafer stage 39 issubjected to the stepping in the non-scanning direction when the imageof the evaluation mark and the opening pattern are relatively movedconcerning the scanning direction. Therefore, the wafer stage 39 may bemerely moved once in each of the scanning direction and the non-scanningdirection by combining the both.

[0126] For example, as shown in FIGS. 3A and 3B, when the position ofthe image 36AP of the evaluation mark 36A in the Y direction ismeasured, then the opening pattern 43 a of the scanning plate 43 ismoved to a position in front of the image 36AP, and then the wafer stage39 is driven to scan the image 36AP with the opening pattern 43 a.During this process, the position information on the wafer stage 39 isalso supplied to the exposure control unit 21 by the aid of the maincontrol system 22. The calculating section in the exposure control unit21 calculates the position of the image 36AP in the Y direction from thesignal which is obtained by differentiating the detection signal of thephotoelectric detector 45 concerning the position of the wafer stage 39in the X direction. Similarly, the position of the image 36AP in the Xdirection is also calculated by scanning the image 36AP in the Xdirection with the opening pattern 43 a. The position information on theimage 36AP in the X direction and the Y direction is supplied to themain control system 22.

[0127] With reference to FIG. 1 again, the evaluation mark plate 33 onthe reticle stage 31, the uneven illuminance sensor 42 on the side ofthe wafer stage 39, and the spatial image-measuring system 46 correspondto the characteristic-measuring system for measuring the predeterminedillumination characteristic (optical characteristic) of the presentinvention.

[0128] Next, an example of the adjusting operation for optimizing thepredetermined illumination characteristic of the illumination opticalsystem of this embodiment will be explained. This embodiment selects, asthe first set of the predetermined illumination characteristic, thedispersion of the illuminance distribution of the exposure light beam ILin the illumination area 35 and consequently in the exposure area 35P(hereinafter referred to as “uneven illuminance”), and the collapseamount of the telecentric property of the exposure light beam IL withrespect to the reticle 28 (hereinafter referred to as “illuminationtelecentricity”), because of the following reason. That is, the twoillumination characteristics most greatly affects the projected imageformed by the projection optical system PL and the photoresist on thewafer W.

[0129] The uneven illuminance is divided into the primary component(referred to as “inclination component”) concerning the position of theexposure area 35P in the non-scanning direction (X direction) and thesecondary component (referred to as “concave/convex component”)concerning the position. That is, assuming that the illuminance isrepresented by a function PF(X) of the position X, the illuminance PF(X)can be approximated as follows. The coefficient a represents theinclination component, and the coefficient b represents theconcave/convex component. In this case, the uneven illuminance componentin the scanning direction (Y direction) is averaged by the scanningexposure. Therefore, the uneven illuminance component in the scanningdirection is not especially an evaluation object in this embodiment. Theconcave/convex component is also a component which is symmetrical withrespect to the optical axis (axially symmetrical component).

PF(X)=a·X+b·X ²+offset  (1A)

[0130] The illumination telecentricity is divided into the inclinationcomponents (shift components) c, d corresponding to the average anglesof inclination in the X direction and the Y direction of the exposurelight beam in the illumination area 35 (exposure area 35P), and themagnification component e corresponding to the average angle ofinclination in the radial direction with respect to the optical axis ofthe exposure light beam. In this case, the focus position of the waferstage 39 is set to the position defocused by ±δ with respect to thefocusing position of the wafer stage 39 in this embodiment. Thepositions (distortion amounts) of images of a large number of evaluationmarks are measured at the respective focus positions by using thespatial image-measuring system 46. The inclination components c, d canbe determined from the average shift amount of the image of theevaluation mark with respect to the amount of change of the focusposition. The magnification component e can be determined by the averageshift amount of the image of the evaluation mark in the radialdirection.

[0131] In this embodiment, as having been explained with reference toFIG. 2, the states of the second fly's eye lens 9, the first lens system12, and the second lens system 13 can be controlled by the aid of thefive driving units 23, 24, 25X , 25Y, 25T respectively. The control asdescribed above makes it possible to control the respective illuminationcharacteristics described above substantially independently as follows.

[0132] (a2) positional adjustment for the second fly's eye lens 9 in theoptical axis direction by the aid of the first driving unit 23:magnification component e [mrad] of the illumination telecentricity;

[0133] (b2) positional adjustment for the first lens system 12 in theoptical axis direction by the aid of the second driving unit 24:concave/convex component b [%] of the uneven illuminance;

[0134] (c2) positional adjustment for the second lens system 13 in the xdirection by the aid of the third driving unit 25X : inclinationcomponent c [mrad] in the X direction of the illuminationtelecentricity;

[0135] (c3) positional adjustment for the second lens system 13 in the ydirection by the aid of the fourth driving unit 25Y: inclinationcomponent d [mrad] in the Y direction of the illuminationtelecentricity;

[0136] (d2) tilt angle adjustment for the second lens system 13 by theaid of the fifth driving unit 25T: inclination component a [%] in thenon-scanning direction of the uneven illuminance.

[0137] As described above, in this embodiment, the combination of theoptical members for which the state can be controlled is optimized sothat only one type of the illumination characteristic (opticalcharacteristic) is substantially changed, and the other illuminationcharacteristics are not changed, when the state of the correspondingoptical member is controlled by using arbitrary one driving unit of theplurality of driving units 23 to 25T. Accordingly, the automaticadjustment for the illumination characteristic can be executed highlyaccurately by means of the simple control. All of the basic illuminationcharacteristics can be automatically controlled by allowing the numberof individuals of the driving units to be five. However, for example,when the illumination characteristic as the control objective is onlythe illumination telecentricity, the number of individuals and thearrangement of the driving units are changed depending on theillumination characteristic of the control objective, for example, suchthat the number of individuals of the driving units is three.

[0138] Actually, it is also feared that other illuminationcharacteristics are slightly affected concerning the five driving units.Therefore, it is desirable to also consider the influence on otherillumination characteristics.

[0139] Accordingly, at first, as shown in a flow chart in FIG. 8, thedriving rate is determined, which indicates how much the correspondingillumination characteristic is successfully changed when the fivedriving units 23, 24, 25X, 25Y, 25T are driven in unit amount.

[0140] That is, in the step 101 shown in FIG. 8, the aperture diaphragmplate 10 shown in FIG. 1 is controlled to set the illumination conditionto any one of those for the ordinary illumination, the modifiedillumination (zonal illumination or four-spot illumination), and thesmall σ value illumination. In the next step 102, the ith driving unit(i=1 to 5) of the five driving units 23 to 25T is selected. In thiscase, it is assumed that the second driving unit 24 corresponding to thefirst lens system 12 is selected. In the next step 103, the drivingamount d2 of the driving unit 24 is set to the center (d2=0) of therange capable of driving, and the first lens system 12 is set at theoptical origin which is the designed position. In this state, the unevenilluminance and the illumination telecentricity are measured.

[0141] In order to measure the uneven illuminance, a glass substrate, onwhich no pattern is formed, is installed in place of the reticle 28 onthe reticle stage 31 shown in FIG. 1. The illumination area 35 isirradiated with the exposure light beam IL. The exposure area 35P isscanned in the non-scanning direction (X direction) with thelight-receiving section of the uneven illuminance sensor 42 toincorporate the detection signal S2 of the uneven illuminance sensor 42into the exposure control unit 21. In place of the glass substrate, anarea in which no pattern is formed in the reticle 28, or an area inwhich no evaluation mark is formed in the evaluation mark plate 33 maybe used.

[0142]FIG. 4A shows a state in which the exposure area 35P is scanned inthe X direction with the light-receiving section 42 a of the unevenilluminance sensor 42. A curve 151A shown in FIG. 4B depicts thedetection signal S2 plotted in this state corresponding to the positionof the uneven illuminance sensor 42 (wafer stage 39) in the X direction.The calculating section in the exposure control unit 21 of thisembodiment calculates the value a1 of the inclination component a of theuneven illuminance and the value b1 of the concave/convex component b byapproximating the curve 151A in accordance with the least square methodwith respect to the right side of the expression (1A). The origin in theX direction in this process is the optical axis AX of the projectionoptical system PL. As depicted by broken lines, when the curve 151A isdivided into a linear straight line 152A and a quadric curve 153A, thenthe slope of the straight line 152A is a1, and the coefficient of X² ofthe quadric curve 153A is b1.

[0143] Subsequently, with reference to FIG. 1, in order to measure theillumination telecentricity, the reticle stage 31 is driven to move thecenter of the evaluation mark plate 33 to the center of the illuminationarea 35. The wafer stage 39 is driven to move the scanning plate 43 ofthe spatial image-measuring system 46 to a position in the vicinity ofthe exposure area 35P. The Z leveling mechanism in the wafer stage 39 isdriven so that the focus position of the scanning plate 43 is set to behigher than the image plane (best focus position) with respect to theprojection optical system PL by +δ (δ is previously set within a rangein which a predetermined resolution is obtained). The radiation of theexposure light beam IL is started. As shown in FIG. 5A, the images 36APto 36 MP of the evaluation marks 36A to 36M of the evaluation mark plate33 are projected onto the wafer stage 39. In this state, as having beenexplained with reference to FIG. 3B, the images 36AP to 36MP are scannedin the X direction and the Y direction with the opening pattern 43 a ofthe scanning plate 43. The obtained detection signal S3 is processed bythe calculating section in the exposure control unit 21. Accordingly,the positions of the images 36AP to 36MP in the X direction and the Ydirection are calculated. The results of the calculation are supplied tothe main control system 22. The origin in this case is, for example, thecenter of the image 36GP of the central evaluation mark 36G. It isdesirable that the movable blind 14B is driven in accordance with themovement of the wafer stage 39 to radiate the exposure light beam ILonto only a part of the illumination area 35, for example, only theevaluation mark for which the image is to be detected by using thespatial image-measuring system 46 during the operation of the detectiondescribed above.

[0144] The images of the evaluation marks 36A to 36M, which are measuredby defocusing the scanning plate 43 by +δ, are designated as images 54Ato 54M on the lattice depicted by broken lines in FIG. 5A. Forconvenience of explanation, the lattice of broken lines is depicted in arectangular configuration, however, it is actually distorted to someextent due to any distortion in some cases.

[0145] Subsequently, the focus position of the scanning plate 43 is setto be lower than the best focus position by −δ. Similarly, the positionsin the X direction and the Y direction of the images 36AP to 36MP of theevaluation marks 36A, 36B, . . . 36M are determined by using the spatialimage-measuring system 46. The obtained results are supplied to the maincontrol system 22. FIG. 5A shows the images 36AP to 36MP in this caseand the images 54A to 54M previously measured. As shown in FIG. 5A, themain control system 22 determines, as vectors <VA>to <VM>, thetwo-dimensional positional discrepancy amounts in the X direction andthe Y direction of the images 36AP to 36MP as obtained when the focusposition is defocused by −δ, with respect to the images 54A to 54M asobtained when the focus position is defocused by +δ. The simple averagevalue <V1>(=(c1, d1)) of the vectors, and the average value <V2>(=e1) ofthe component in the radial direction (R direction) with respect to theorigin are calculated as shown in FIGS. 5B and 5C. The average value(c1, d1) is the inclination component of the illuminationtelecentricity, and the average value e1 is the magnification componentof the illumination telecentricity.

[0146] Subsequently, in the step 104, the uneven illuminance and theillumination telecentricity are measured in a state in which the drivingamount d2 of the driving unit 24 is set to the end (d2=d2max) on theplus side in the range capable of driving. Accordingly, as shown in FIG.4C, a curve 151B of the detection signal S2 of the uneven illuminancesensor 42 is obtained. The curve 151B is divided into a linear straightline 152B and a quadric curve 153B. Thus, the inclination component a2and the concave/convex component b2 of the uneven illuminance areobtained. As shown in FIGS. 5E and 5F, the inclination component (c2,d2) of the illumination telecentricity and the magnification componente2 of the illumination telecentricity are obtained from the vectors<VA>to <VM>of the positional discrepancy of the images 36AP to 36MP ofthe evaluation marks 36A to 36M shown in FIG. 5D.

[0147] Subsequently, in the step 105, the uneven illuminance and theillumination telecentricity are measured in a state in which the drivingamount d2 of the driving unit 24 is set to the end (d2=−d2max) on theminus side in the range capable of driving. Accordingly, the inclinationcomponent a3 of the uneven illuminance, the concave/convex component b3,the inclination component (c3, d3) of the illumination telecentricity,and the magnification component e3 are obtained in the same manner asdescribed above. When it is intended to calculate the driving rate morehighly accurately, it is desirable that the driving amount of thedriving unit 24 is set to four or more to measure the uneven illuminanceand the illumination telecentricity.

[0148] In the subsequent step 106, the driving rate of the driving unit24 (first lens system 12) is calculated by using the measured valuesdescribed above. For example, the inclination components a, which areobtained when the driving amount d2 is set to 0, d2max, and −d2max, area1, a2, and a3 respectively. Therefore, the driving rate ka2 [%/mm] withrespect to the inclination component a is as follows.

ka2=[(a2−a1)/d2max−(a3−a1)/(2·d2max)]/2  (1B)

[0149] Similarly, the driving rates kb2 [%/mm], kc2 [mrad/mm], kd2[mrad/mm], and ke2 [mrad/mm] are also calculated with respect to theconcave/convex component b of the uneven illuminance, the inclinationcomponents c, d of the illumination telecentricity, and themagnification component e of the illumination telecentricity. Thedriving rates are stored in a storage unit in the main control system22.

[0150] In this process, the dominant value is only the driving rate kb2with respect to the concave/convex component b of the unevenilluminance. However, even in the case of the other value, thoseexceeding predetermined levels may be stored as they are. Values withinthe predetermined levels may be stored as zero.

[0151] Specifically, when the first lens system 12 is driven, there issuch a possibility that the driving rate ke2 with respect to themagnification component e of the illumination telecentricity having thecharacteristic of centro-symmetry (axial symmetry) may exceed thepredetermined level in the same manner as the concave/convex componentb.

[0152] The operations ranging from the step 102 to the step 106 areexecuted for all of the driving units 23 to 25T as described above tocalculate the driving rates kai, kbi, kci, kdi, kei (i=1 to 5) which arestored as parameters for each of the illumination conditions in the maincontrol system 22. After that, the routine proceeds from the step 107 tothe step 108 to judge whether or not the driving rate is calculated forall of the necessary illumination conditions. If the calculation is notcompleted, the routine returns to the step 101 to switch theillumination condition and calculate the driving rate. The driving ratehas been calculated for all of the illumination conditions. However,this embodiment is not limited thereto. For example, the driving ratemay be calculated for a part of all of the illumination conditions. Thedriving rate may be determined for the remaining illuminationconditions, for example, by means of the interpolation calculation onthe basis of the driving rates of other illumination conditions.

[0153] In this process, in the case of the second driving unit 24 (firstlens system 12), the driving rates ka2, kc2, kd2 concerning thecentro-asymmetrical components are amounts of such extents that they areoriginally negligible. If such a driving rate is large to be not lessthan a certain value, there is such a possibility that the first lenssystem 12 is eccentric or inclined. At this stage, it is possible tosense such an inconvenience. Based on this result, it is possible toperform the adjustment.

[0154] Next, explanation will be made with reference to a flow chartshown in FIG. 9 for an example of the sequence to automatically adjustthe illumination optical system by using the driving rates determined asdescribed above.

[0155] At first, in the step 111 shown in FIG. 9, the illuminationcondition is selected by the aid of the aperture diaphragm plate 10shown in FIG. 1. The driving amounts of all of the driving units 23, 24,25X to 25T are set to the neutral position. The corresponding opticalmember is set to the optical origin. In the next step 112, the unevenilluminance and the illumination telecentricity are measured in the samemanner as in the step 103 shown in FIG. 8. In the step 113, theinclination component (primary component) a and the concave/convexcomponent (secondary component) b of the uneven illuminance arecalculated in accordance with the procedure shown in FIG. 5. Further,the inclination components (shift components) c, d and the magnificationcomponent e of the illumination telecentricity are calculated. In thenext step 114, it is judged whether or not the uneven illuminance a, band the illumination telecentricity c, d, e are within allowable rangesrespectively. If any one of them is deviated from the allowable range,the routine proceeds to the step 115 to calculate the driving amounts di(i=1 to 5) of the five driving units 23 to 25T to make the unevenilluminance a, b and the illumination telecentricity c, d, e to be zeroon calculation with the driving rates kai, kbi, kci, kdi, kei (i=1 to 5)stored in the main control system 22. In this case, the followingsimultaneous equations may be solved.

−a=ka1·d1+ka2·d2+ka3·d3+ka4·d4+ka5·d5

−b=kb1·d1+kb2·d2+kb3·d3+kb4·d4+kb5·d5

−c=kc1·d1+kc2·d2+kc3·d3+kc4·d4+kc5·d5

−d=kd1·d1+kd2·d2+kd3·d3+kd4·d4+kd5·d5

−e=ke1·d1+ke2·d2+ke3·d3+ke4·d4+ke5·d5

[0156] However, actually, the number of those which are not zero of thedriving rates is about one or two in each row. Therefore, thesimultaneous equations can be solved extremely easily. The calculateddriving amounts di (i=1 to 5) are also stored in the storage unit in themain control system 22 as parameters corresponding to each of theplurality of illumination conditions.

[0157] Specifically, it is considered that the following relationship isprovided. That is, both of the driving unit 24 and the driving unit 23affect the concave/convex component b of the uneven illuminance and themagnification component e of the illumination telecentricity. Both ofthe driving unit 25T and the driving unit 25X affect the inclinationcomponent a of the uneven illuminance and the inclination component c ofthe illumination telecentricity. Only the driving unit 25Y affects theinclination component d of the illumination telecentricity.

[0158] Subsequently, the routine proceeds to the step 116 to drive thefive driving units 23 to 25T in the calculated driving amounts di (i=1to 5) respectively. After that, the routine proceeds to the steps 112and 113 to measure the uneven illuminance a, b and the illuminationtelecentricity c, d, e again. In the step 114, if all of their valuesare not included in the allowable ranges, the routine proceeds to thestep 115 again to execute the calculation. If all of the values areincluded within the allowable ranges, the automatic adjustment iscompleted. When the same illumination condition is set next time, theadjustment for the illumination optical system is completed for anextremely short period of time only by driving the driving units 23 to25T on the basis of the stored driving amounts di.

[0159] As described above, in this embodiment, the illuminationcharacteristic can be automatically measured. Therefore, all of themeasurement sequence for the driving rate shown in FIG. 8 and theautomatic adjustment sequence for the illumination optical system shownin FIG. 9 can be performed in an assist-less manner.

Second Embodiment

[0160] Next, explanation will be made for an example of the adjustingmethod adopted when the modified illumination is performed by installingthe aperture diaphragm 10 b for the zonal illumination (or the aperturediaphragm 10 c for the four-spot illumination) at the light-outgoingplane of the second fly's eye lens 9 as shown in FIG. 6A with theillumination optical system of this embodiment.

[0161] In this case, the light amount distribution-converting element55, which is composed of a diffractive optical element (DOE), isinstalled in place of the first fly's eye lens 6 shown in FIG. 1. Inplace of the diffractive optical element, a prism including, forexample, a conical prism (axicon for zonal illumination) and a prism ofthe quadrangular pyramid type (pyramid type) (for four-spotillumination) may be used. In order to adjust the illumination area ofthe exposure light beam IL with respect to the second fly's eye lens 9depending on whether the aperture diaphragm to be used is the aperturediaphragm 10 b or 10 c, the arrangement is made such that the first lenssystem 7A can be driven in the direction perpendicular to the opticalaxis by the aid of the driving unit 62, and the second lens system 7Bcan be driven in the optical axis direction by the aid of the drivingunit 58. A zoom optical signal, an optical signal to continuously changethe aberration, or an optical signal to distort the cross section of thebeam by rotating a cylindrical lens may be used in place of thelight-collecting optical system (beam-shaping optical system) composedof the lens systems 7A, 7B.

[0162] In the case of the optical system shown in FIG. 6A, it has beenconfirmed by the present inventors that the uneven illuminance isquickly changed depending on the illumination area used when the secondfly's eye lens 9 is locally illuminated. The factor of the change of theuneven illuminance is specifically divided into the following factors.

[0163] (1) When the local illumination area is small, the image planeilluminance is increased, because the amount of light passing throughthe aperture diaphragm is large. However, some of the effective elementsof the second fly's eye lens 9 are illuminated in a half-finishedmanner. This badly affects the uneven illuminance.

[0164] (2) When the local illumination area is large, the unevenilluminance is not deteriorated. However, of course, the amount of lightshielded by the aperture diaphragm 10 b, 10 c is increased, and theimage plane illuminance is lowered.

[0165] (3) When the local illumination area is eccentric, there is sucha tendency that the uneven illuminance on the image plane is alsolowered on any of the right and left sides (inclination component). Thisresults from the fact that each of the elements of the second fly's eyelens 9 has the finite size. Accordingly, in this embodiment, when themodified illumination is performed with the light amountdistribution-converting element 55, a special adjustment sequence isprepared as shown in FIG. 10.

[0166] In the step 121 shown in FIG. 10, the measurement of the drivingrate shown in FIG. 8 and the automatic adjustment sequence shown in FIG.9 are executed in the state shown in FIG. 1, i.e., by setting theordinary illumination. In the next step 122, as shown in FIG. 6A, thefirst fly's eye lens 6 is changed to the light amountdistribution-converting element 55, and the aperture diaphragm at thelight-outgoing plane of the second fly's eye lens 9 is set to theaperture diaphragm 10 b or 10 c for the modified illumination. In thenext step 123, the uneven illuminance is measured by using the unevenilluminance sensor 42 shown in FIG. 1. The inclination component a andthe concave/convex component b thereof are calculated as shown in FIG.4. In this process, if the uneven illuminance having an extremeinclination appears on the both sides of the illuminance distribution inthe non-scanning direction, and the inclination component a exceeds theallowable range, then there is such a possibility that the localillumination area is eccentric as described above. In this case, inorder to allow the inclination component a to be included within theallowable range, the first lens system 7A is shifted in the directioncorresponding to the X direction or the Y direction in the planeperpendicular to the optical axis.

[0167] The concave/convex component b of the uneven illuminance isregarded to be the evaluation object in this state. That is, the routineproceeds to the step 124 to judge whether or not the concave/convexcomponent b is within the allowable range. If the concave/convexcomponent b is without the allowable range, the routine proceeds to thestep 125 to shift the second lens system 7B in a predetermined stepamount in the optical axis direction. After that, the routine returns tothe step 123, and the concave/convex component b of the unevenilluminance is measured again to judge whether or not the concave/convexcomponent b is within the allowable range. The correcting operation isexecuted until the concave/convex component b is included in theallowable range in the step 124.

[0168] After the concave/convex component b is included within theallowable range in the step 124, the routine proceeds to the step 126.The lens system 4B of the beam-shaping system 5 shown in FIG. 6A isgradually changed (scanned) by a predetermined amount in the opticalaxis direction. The uneven illuminance sensor 42 shown in FIG. 1 isscanned in the non-scanning direction at the respective positions(positions u) of the lens system 4B in the exposure area 35P includingno pattern image. The data array of the detection signals S2 isincorporated into the exposure control unit 21. Further, the detectionsignal S1 of the integrator sensor 20 is also incorporated into theexposure control unit 21.

[0169] In the next step 127, the difference ΔIP between the maximumvalue and the minimum value of the detection signal S2 (illuminance) isdetermined as the uneven illuminance at the respective positions u ofthe lens system 4B. The magnitude of the illuminance (average value) IPon the image plane is indirectly determined from the detection signal S1of the integrator sensor 20. The calculating section in the exposurecontrol unit 21 allows the reciprocal (1/ΔIP) of the uneven illuminanceΔIP and the image plane illuminance IP to correspond to the respectivepositions u of the lens system 4B. FIG. 7 shows a diagram obtained byplotting the image plane illuminance IP and the reciprocal (1/ΔIP) ofthe uneven illuminance with respect to the position u for the purpose ofbetter understanding.

[0170] In FIG. 7, the horizontal axis represents the position u of thelens system 4B, and the vertical axis represents the image planeilluminance IP and the reciprocal (1/ΔIP) of the uneven illuminance ΔIP.A curve 59 indicates the image plane illuminance IP, and a curve 60indicates the reciprocal (1/ΔIP) of the uneven illuminance. In thiscase, when the image plane illuminance IP is increased, then thereciprocal (1/ΔIP) of the uneven illuminance is decreased, and theuneven illuminance is increased. Therefore, it is understood that theimage plane illuminance and the uneven illuminance are in therelationship of trade-off. Accordingly, in this embodiment, the range 61of the position u (u1≦u≦u2), in which the image plane illuminance is notless than the allowable value TL1(position u2) and the reciprocal of theuneven illuminance is not less than the allowable value TL2 (positionu1), is determined as the settable range for the lens system 4B, and therange 61 is supplied to the main control system 22.

[0171] In the next step 128, the main control system 22 shown in FIG. 1sets the position u of the lens system 4B shown in FIG. 6A to be withinthe settable range 61 by the aid of the driving system 26. Accordingly,a high image plane illuminance is obtained to successfully improve thethroughput of the exposure step. Further, the uneven illuminance isdecreased, and it is possible to obtain a high image formation accuracy.

[0172] If any fine and random uneven illuminance is measured on theimage plane, when the optical element for the modified illumination isshifted in the optical axis direction, then the random unevenilluminance can be dissolved in some cases. As described above, thevarious characteristics of the illumination optical system are changedby driving the arbitrary optical member of the illumination opticalsystem. However, when they are selected at the stage of design, and theoptimum driving unit is incorporated into the automatic adjustmentsequence, then it is possible to further improve the chasing accuracyfor the uneven illuminance and the illumination telecentricity.

[0173] In the embodiment described above, both of the uneven illuminanceand the collapse amount of the telecentricity are measured (detected).However, only any one of them may be measured. Further, as for thecollapse amount of the telecentricity, the inclination component isdivided into those in the X direction and the Y direction to perform themeasurement. However, any one of them may be sufficient in some cases.In the embodiment described above, the uneven illuminance in thenon-scanning direction is detected in the scanning exposure apparatus.However, in the case of the static exposure system, it is preferablethat the uneven illuminance is detected in the X direction and the Ydirection respectively to perform the correction therefor.

[0174] In FIG. 6A, the light amount distribution-converting element 55is arranged in the optical path of the exposure light beam while beingexchanged with the first fly's eye lens 6 during the modifiedillumination. However, for example, the light amountdistribution-converting element 55 may be arranged between the exposurelight source 1 and the optical integrator (first fly's eye lens 6 inthis embodiment). In this case, the light amount distribution-convertingelement 55 may be exchanged with another element for generating adifferent light amount distribution, depending on the change of theillumination condition. Further, also in the illustrative arrangementshown in FIG. 6A, the light amount distribution-converting element 55may be exchanged for those for the zonal illumination and the four-spotillumination.

Third Embodiment

[0175] This embodiment is illustrative of a case in which a filter(member) of the present invention is used. FIG. 11 shows a schematicarrangement of a scanning exposure type projection exposure apparatusbased on the step-and-scan system of this embodiment. This exposureapparatus has substantially the same structure as that of the exposureapparatus according to the first embodiment except that a concentrationfilter plate 51 corresponding to a planer area with a variabletransmittance distribution is provided, the driving system for the fly'seye lens 9 is not provided, and the structure of the driving system 25is different from that in the first embodiment.

[0176] The concentration filter plate 51 is provided in the illuminationoptical system ISL. More specifically, the concentration filter plate 51is arranged at the plane which is further defocused by a predeterminedamount from the fixed blind 14A, i.e., at the plane which is slightlydefocused from the conjugate plane with respect to the reticle plane.When the concentration filter plate 51 is arranged at the plane which isslightly defocused from the conjugate plane with respect to the reticleplane, any image of foreign matters such as dust or the like adhered tothe concentration filter plate 51 can be prevented from transfer ontothe wafer W. Alternatively, the image of the concentration filter plate51 or the foreign matter may be made to be ambiguous in the illuminationarea 35, i.e., the decrease in illuminance uniformity and consequentlythe decrease in uniformity of the exposure amount distribution on thewafer W may be avoided, for example, by driving an optical element (forexample, at least one of the lens systems 16 to 18 or an unillustrateddiffusion plate) arranged between the concentration filter plate 51 andthe reticle in place of or in combination of the arrangement of theconcentration filter plate 51 at the defocused plane.

[0177] The concentration filter plate 51 may be arranged at the planewhich is close to the light-outgoing side of the movable blind 14, noton the light-incoming side of the fixed blind 14A. Alternatively, forexample, the fixed blind 14A may be arranged at the plane in thevicinity of the pattern plane (reticle plane) of the reticle 28, forexample, at the plane close to the upper surface of the reticle 28. Theconcentration filter plate 51 may be arranged at the plane which isdefocused by a predetermined spacing distance on the input side of themovable blind 14B shown in FIG. 11. Accordingly, the concentrationfilter plate 51 can be easily arranged.

[0178] Alternatively, the concentration filter plate 51 may be arrangedat the plane which is separated from another conjugate plane withrespect to the image plane (i.e., the conjugate plane with respect tothe reticle plane) which is different from the plane (conjugate planewith respect to the image plane) at which the movable blind 14B isarranged in the illumination optical system ILS. For example, in FIG.11, the concentration filter plate 51 may be arranged at the plane inthe vicinity of the pattern plane of the reticle 28, for example, at theplane separated by a predetermined spacing distance from the uppersurface or the lower surface of the reticle 28, in a state in which thefixed blind 14A is arranged in the vicinity of the movable blind 14B.Further, when the projection optical system PL forms an intermediateimage at the inside, the concentration filter plate 51 may be arrangedat the plane separated from the plane of the formation of theintermediate image. Further, as for the movable blind 14B, anarrangement is also available, in which the movable blind 14B isarranged, for example, closely to the reticle plane.

[0179] Driving units 24, 25, 52 are installed to the lens systems 12, 13and the concentration filter plate 51 of this embodiment respectively.FIG. 12 shows a perspective view illustrating the relationship betweenthe illumination area 35 and the optical system ranging from the secondfly's eye lens 9 to the fixed blind 14A shown in FIG. 11. In FIG. 12,the scanning direction SD (Y direction) of the reticle with respect tothe illumination area 35, and the direction on the fixed blind 14Acorresponding to the non-scanning direction (X direction) are designatedas the Y direction and the X direction respectively. Only theslit-shaped opening of the fixed blind 14A (fixed field diaphragm) isillustrated in the drawing.

[0180] In this arrangement, the driving unit 24 adjusts the position ofthe first lens system 12 in the direction of the optical axis IAX. Thedriving unit 25 shown in FIG. 11 is different from that in the firstembodiment, which is constructed by a driving unit 25R shown in FIG. 12.The driving unit 25R adjusts the tilt angle (angle of inclination) aboutthe axis which passes through the optical axis IAX of the second lenssystem 13 and which is parallel to the Y axis, i.e., the tilt angle inthe direction corresponding to the non-scanning direction of theillumination area 35. Reference may be made to the arrow TX shown inFIG. 12. Further, the driving unit 52 shown in FIG. 11 includes a gearsection 52G which is installed to the periphery of the disk-shapedconcentration filter plate 51 shown in FIG. 12 by the aid of anunillustrated ring-shaped holder, and a driving section 52W whichincludes a gear and a motor for driving and rotating the gear section52G. The arrangement is made such that the concentration filter plate 51is rotatable by a desired angle θ within a range of 90° about the centerof the optical axis IAX by the aid of the driving unit 52.

[0181] Those usable as the driving units 24, 25R include, for example, adriving unit for displacing the holder of the optical element as thedriving objective with a driving element such as a micrometer based onthe electric system and a piezoelectric element. In this arrangement, anencoder (for example, a rotary encoder) (not shown), which indicates thedisplacement amount of the optical element in the range capable ofdriving (driving stroke), is incorporated into each of the driving units24, 25R and the driving section 52W. Detection signals of the encodersare supplied to the driving system 26 shown in FIG. 11. The drivingsystem 26 controls the states of the lens systems 12, 13 and theconcentration filter plate 51 by the aid of the driving units 24, 25, 52on the basis of the detection signals and the driving informationsupplied from the main control system 22.

[0182] In this arrangement, as having been explained in the firstembodiment, the centro-symmetrical unevenness (quadratic function-likeunevenness), which is the uneven illuminance axially symmetrical inrelation to the optical axis, is corrected by driving the first lenssystem 12 in the optical axis direction. The inclination unevenness(linear function-like unevenness), which is the uneven illuminance withthe illuminance gradually increasing or decreasing in the areaintersecting the optical axis, is corrected by controlling the tiltangle of the second lens system 13. The angle of rotation of theconcentration filter plate 51 is controlled in order that the uniformityof the exposure amount distribution on the wafer W is finally includedin a predetermined allowable range (as described in detail later on). Inthis embodiment, the centro-symmetrical unevenness can be substantiallycorrected by controlling the angle of rotation of the concentrationfilter plate 51. Therefore, the driving unit 24 for the first lenssystem 12 may be omitted. Accordingly, it is possible to simplify themechanism of the illumination optical system.

[0183] An uneven illuminance sensor 42, which serves as the exposureamount distribution-measuring unit, is installed in the vicinity of thewafer holder 38 on the wafer stage 39 of this embodiment. As shown inFIG. 13A, the uneven illuminance sensor 42 is provided with a firstsensor which is composed of a photoelectric sensor having a pinhole-shaped light-receiving section 42 a, and a line sensor 42 b (secondsensor) which has one array of photoelectric conversion elements(picture elements or image pixels) arranged in a slender configurationin the scanning direction SD (Y direction). The photoelectric conversionsignal of any one of the first sensor and the second sensor is suppliedas the detection signal S4 to the exposure control unit 21 shown in FIG.11 in accordance with the control information supplied from the maincontrol system 22.

[0184] With reference to FIG. 13A, the length of the line sensor 42 b inthe scanning direction SD is set to be wider than the width of theexposure area 35P in the scanning direction SD. When the unevenilluminance in the non-scanning direction (X direction) in the exposurearea 35P is measured, the wafer stage 39 shown in FIG. 11 is driven toarrange the line sensor 42 b of the uneven illuminance sensor 42 on theside surface of the exposure area 35P in the X direction. Thephotoelectric conversion signal, which is read by the line sensor 42 b,is supplied as the detection signal S4 to the exposure control unit 21.After that, the light emission of the exposure light source 1 isstarted. The wafer stage 39 is driven to move the line sensor 42 b to aplurality of measuring point arranged at predetermined spacing distancesin the X direction so that the exposure area 35P is traversed. Anadded-up signal, which is obtained by adding up the detection signals ofthe line sensor 42 b in the Y direction, is determined by the exposurecontrol unit 21 at the respective measuring points. The added-up signalis supplied to the main control system 22. Actually, the exposure lightbeam IL involves any dispersion of energy to some extent for each pulselight emission. Therefore, the added-up signal is normalized with thedetection signal S1 of the integrator sensor 20 shown in FIG. 11. Themain control system 22 stores the normalized added-up signal (referredto as “S4” as well) in the storage unit as corresponding to the positionX of the line sensor 42 b in the non-scanning direction.

[0185]FIG. 13B illustrates an example of the added-up signal S4. In FIG.13B, the horizontal axis represents the position X of the line sensor 42b in the non-scanning direction, and the vertical axis represents theadded-up signal S4. The added-up signal S4 is substantially equal to theexposure amount obtained by adding up the exposure amounts of theexposure area 35P in the scanning direction at the respective measuringpoints in the non-scanning direction, i.e., the exposure amount(added-up exposure amount) given to the predetermined point on the waferby the scanning exposure. Therefore, the added-up signal S4substantially represents the distribution (exposure amount unevenness)in the non-scanning direction of the exposure amount (added-up exposureamount) after performing the scanning exposure for the respective shotareas on the wafer with the exposure area 35P.

[0186] In FIG. 13B, when the added-up signal S4 is flat with respect tothe position X as represented by a straight line 153A, it is indicatedthat there is no unevenness of the exposure amount in the non-scanningdirection. In this state, it is possible to obtain high uniformity (highexposure amount accuracy) of the exposure amount distribution. On theother hand, when the added-up signal S4 represents a centrally concavedistribution in which it is decreased at a central portion including theoptical axis AX as indicated by a curve 153B, it is understood that theexposure amount unevenness which is axially symmetrical in relation tothe optical axis, i.e., the axially symmetrical uneven illuminance(centro-symmetrical unevenness) appears. In order to correct theunevenness, for example, the concentration filter plate 51 shown in FIG.11 may be used to relatively increase the transmittance in the vicinityof the optical axis. Further, when the added-up signal S4 represents theinclination unevenness which gradually increases to traverse the opticalaxis AX as indicated by a straight line 153C, for example, the tiltangle of the second lens system 13 shown in FIG. 11 may be controlled inorder to correct the unevenness. In this embodiment, the unevenness ofthe exposure amount in the non-scanning direction after the scanningexposure, i.e., the uneven illuminance in the non-scanning direction canbe easily measured by using the line sensor 42 b as described above.Further, the uneven illuminance in the X direction and Y direction inthe exposure area 35P can be also measured by moving the pin hole-shapedlight-receiving section 42 a shown in FIG. 13A to the plurality ofmeasuring points installed two-dimensionally in the exposure area 35P tomeasure the illuminances respectively. Further, the exposure amountdistribution (exposure amount unevenness) concerning the non-scanningdirection can be also obtained in the same manner as in thelight-receiving section 42 a described above by adding up theilluminances at the respective measuring points concerning the scanningdirection (Y direction) at the respective positions in the non-scanningdirection (X direction) in the exposure area 35P to determine theadded-up light amount (exposure amount) of the exposure light beam IL.In this procedure, the illuminance may be measured at the respectivemeasuring points while stepping the light-receiving section 42 a in thescanning direction at the respective positions in the non-scanningdirection. However, it is preferable that the light-receiving section 42a is relatively moved in the scanning direction with respect to theexposure area 35P at the respective positions in the non-scanningdirection, and the oscillation (oscillation frequency and pulse energy)of the exposure light source 1 and the movement velocity of the waferstage 39 are controlled under the same condition as that of the scanningexposure for the wafer W. Accordingly, the exposure light beam IL, whichas the same number of pulses as that during the scanning exposure, isradiated onto the light-receiving section 42 a during the period inwhich the light-receiving section 42 a traverses the exposure area 35P.The added-up light amount (exposure amount) of the exposure light beamIL can be correctly measured at the respective positions in thenon-scanning direction. Therefore, although the uneven illuminancesensor 42 has the light-receiving sections 42 a, 42 b in thisembodiment, the uneven illuminance sensor 42 may be provided with onlyone of the light-receiving sections 42 a, 42 b. As for thelight-receiving section 42 b described above, the number of thelight-receiving elements (arrays) arranged in the exposure area 35P whenthe added-up light amount (exposure amount) of the exposure light beamIL is measured at the respective positions in the non-scanning directionmay be the same as the number of the pulses radiated onto the respectivepoints on the wafer when the scanning exposure is performed. In thiscase, for example, it is preferable that the same number of the exposurelight beams IL as those used during the scanning exposure are radiated,and the outputs of the light-receiving elements different for each ofthe pulses are added up to determine the added-up light amount.

[0187] The exposure light beam IL of this embodiment is a substantiallyvacuum ultraviolet ray (VUV) having a wavelength of not more than 200nm. The light beam is greatly absorbed by light-absorbing substancessuch as steam and carbon dioxide. The absorption by oxygen is graduallyincreased. Accordingly, the purge gas, which is a gas from which suchlight-absorbing substances are removed, and organic matters and finedust or the like are removed by using, for example, a chemical filter oran HEPA filter (high efficiency particulate air-filter), is supplied tothe optical path for the exposure light beam IL ranging from theexposure light source 1 to the wafer W shown in FIG. 11. Those usable asthe purge gas include, for example, dry air, nitrogen gas, and heliumgas.

[0188] Even when the purge gas, from which organic matters or the likeare highly removed as described above, is used, a minute amount ofremaining organic matters or the like cause the chemical reaction withthe exposure light beam IL. Cloudy substances gradually adhere to thesurfaces of the respective optical elements in the illumination opticalsystem ILS and the projection optical system PL. As a result, thetransmittance distribution is changed, and any uneven illuminance occursin the exposure area 35P on the wafer W in a time-dependent manner. Theuneven illuminance caused by the cloudy substance tends to form thecentro-symmetrical unevenness (quadratic function-like unevenness) whichis axially symmetrical in relation to the optical axis AX (coincidentwith the exposure center in this embodiment). Especially, there is sucha tendency that the uneven illuminance, in which the illuminance islowered at the central portion in the vicinity of the optical axis AX(hereinafter referred to as “centrally concave unevenness”), is caused.Accordingly, in this embodiment, the centro-symmetrical unevenness(especially the centrally concave unevenness), which is principallycaused in the time-depending manner as described above, is corrected byusing the rotatable concentration filter plate 51 shown in FIG. 11.

[0189] Explanation will be made in detail below for an example of thearrangement and the method of the use of the rotatable concentrationfilter plate 51. FIG. 14A shows the arrangement of the concentrationfilter plate 51 shown in FIG. 11 (or FIG. 12) in the initial state. Withreference to FIG. 14A, the concentration filter plate 51 is providedwith a predetermined light-shielding substance or a dimming substancesuch as metal (for example, chromium) which is deposited, for example,by means of vapor deposition on a first surface of a flat disk-shapedglass substrate which transmits the exposure light beam so that apredetermined one-dimensional transmittance distribution T(X) isobtained axially symmetrically in relation to the optical axis IAX. InFIG. 14A, the portion having the denser black color is deposited with alarger amount of the substance, and the transmittance is lowered at theportion in accordance therewith.

[0190] In FIG. 14A, the direction of the concentration filter plate 51to have the transmittance distribution is set to be in the Y direction(scanning direction) with respect to the fixed blind 14A (represented bythe slit-shaped opening as in the same manner in the followings). Thetransmittance T(Y) in the Y direction is represented as follows by usinga coefficient a.

T(Y)=1/(a·Y ²+1)  (2A)

[0191] This function is determined to offset the quadratic function-likeunevenness, resulting from the fact that the centro-symmetricalunevenness ordinary forms the quadratic function-like unevenness. Thisfunction is determined in various ways depending on the (expected)amount of generation of the actual centro-symmetrical unevenness. Thecoefficient a in the expression (2A) is a parameter to determine themaximum correction amount of the concentration filter plate 51. Assumingthat R represents the radius of the concentration filter plate 51 and Drepresents the maximum correction amount for the transmittance at theoutermost periphery of the concentration filter plate 51, thecoefficient a is represented as follows. The maximum correction amount Dis, for example, 0.1 (10%).

a=D/{(1−D)R ²}  (2B)

[0192] In this embodiment, it is assumed that the uneven illuminance,which is caused by the cloudy substance gradually adhered to the opticalelement in the optical system, is successfully corrected by one sheet ofthe concentration filter plate 51, even when the projection exposureapparatus shown in FIG. 11 is operated in the actual exposure step fornot less than about two years. If the degree of the centro-symmetricalunevenness in the exposure area 35P, especially the centrally concaveunevenness, which is caused after using the projection exposureapparatus for two years, is about 10% in range, the value of thecoefficient a in the expression (2B) is as follows.

a=0.1/(0.9·R ²)  (2C)

[0193] As shown in FIGS. 14A to 14C, the concentration filter plate 51is rotatable by an arbitrary angle θ within a range of 90° about thecenter of the optical axis IAX.

[0194]FIG. 14A shows a state in which the concentration filter plate 51is not rotated, i.e., the angle θ is 0°. In this state, the averagetransmittance T(X) in the non-scanning direction (X direction) in theopening of the fixed blind 14A is flat as indicated by a straight line154A. The function to adjust the uneven illuminance in the non-scanningdirection is not operated. In the following drawings, it is assumed thatthe X coordinate at the optical axis IAX is 0. The transmittancedistribution is high at the central portion with respect to the scanningdirection (Y direction). The uneven illuminance caused thereby isaveraged by means of the scanning exposure.

[0195] On the other hand, FIG. 14C illustrates a case in which theconcentration filter plate 51 is rotated by 90°, in order to correct thecentrally concave unevenness extremely advanced by the time-dependentchange. In this case, the transmittance T(X) in the non-scanningdirection is as follows.

T(X)=1/(a·X ²+1)  (3)

[0196] In this case, the difference between the maximum value and theminimum value is maximized as indicated by a curve 154C for thedistribution of the transmittance T(X). The effect of correcting thecentrally concave unevenness by the concentration filter plate 51 ismaximized. The value T′ of the minimum value of the curve 154C is 0.9(90%) according to the expression (2B).

[0197]FIG. 14B shows a state in which the concentration filter plate 51is rotated by 45° (0=45°). In this case, the transmittance T (X, Y, θ)corresponding to each of the points in the opening of the fixed blind14A (corresponding to the exposure area 35P on the wafer) is as follows.

T(X,Y,θ)=1/{a(X sin θ−Y cos θ)²+1}  (4)

[0198] The transmittance T(X) in the non-scanning direction, which isobtained by averaging the transmittance in the Y direction, isrepresented by a curve 154B. Accordingly, it is understood that thecorrecting is effect is obtained for the centrally concave unevenness ofan intermediate degree between those of θ=90° and θ=0°.

[0199] As shown in FIGS. 14A to 14C, the average transmittancedistribution in the non-scanning direction can be regulated to have anarbitrary characteristic by rotating the concentration filter plate 51to have an arbitrary angle. It is possible to successively correct thecentrally concave unevenness caused by the variation of radiation in thetime-dependent manner. Further, the concentration filter plate 51 is athin flat plate which is installed in the vicinity of the conjugateplane with respect to the image plane. Therefore, the uniformity of thecoherence factor (σ value) of the illumination optical system isscarcely affected when the uneven illuminance is corrected. That is, oncondition that the uniformity of the σ value is previously adjusted tobe within a predetermined allowable range in the initial state, theuniformity of the σ value is not deteriorated even when the unevenilluminance due to the time-dependent change is corrected. Thus, it ispossible to always obtain high line width uniformity.

[0200] The mechanism for rotating the concentration filter plate 51 isbased on the electric system (automatic control system). Therefore, forexample, the uneven exposure amount (uneven illuminance) in thenon-scanning direction may be measured as shown in FIG. 13 by using theuneven illuminance sensor 42 during the periodic maintenance, and theconcentration filter plate 51 can be driven and rotated at an optimumangle to offset the uneven exposure amount in situ. Further, the degreeof the centrally concave unevenness may be determined by approximatecalculation at an arbitrary period of elapse time by temporally managingthe projection exposure apparatus for a long period of time, or managingthe total radiation amount. The concentration filter plate 51 can bealso rotated automatically (in real time) so that the centrally concaveunevenness is corrected.

[0201] Further, the correction can be also made for the differencebetween a plurality of illumination conditions concerning the unevenilluminance initially generated. The concentration filter plate 51 ofthis embodiment has only the function to make the centrally concaveunevenness to be flat. However, for example, a fixed concentrationfilter plate or the like may be previously inserted in the vicinity ofthe concentration filter plate 51 shown in FIG. 12. The unevenilluminance under all of the illumination conditions may be made toslight centrally concave unevenness. The difference may be corrected byrotating the concentration filter plate 51. Accordingly, it is possibleto suppress the occurrence of the uneven illuminance even when theillumination condition is switched between the ordinary illumination andthe modified illumination. The concentration filter plate 51 of thisembodiment can be electrically controlled. Therefore, the concentrationfilter plate 51 may be rotated up to an optimum angle every time whenthe illumination condition is switched. Slight illumination lossinitially appears in all cases. However, actually, it is possible tosuppress the illumination loss to be not more than about 5%.

[0202] The concentration filter plate 51 can be produced in accordancewith a variety of production methods as shown in FIG. 15. In theconcentration filter plate 51 shown in FIG. 15A, the transmittancedistribution, which is continuously changed in the Y direction, isobtained by vapor-depositing a dimming substance such as chromium (Cr)on a light-transmissive substrate while continuously changing the filmthickness. The metal such as chromium behaves as a light-shieldingsubstance in the case of an ordinary film thickness. However, in thisembodiment, chromium or the like is used as the dimming substance in aregion of the film thickness in which the light is transmitted to someextent. In the concentration filter plate 51G shown in FIG. 15B, a firstsurface of a substrate is divided into a plurality of band-shaped areasin the Y direction, and a dielectric multilayered film is formed in theband-shaped areas so that predetermined transmittances are obtainedrespectively. That is, in the concentration filter plate 51G, thetransmittance distribution is changed in a stepwise manner in the Ydirection. However, the number of division is increased to be not lessthan about 10, it is possible to obtain the correcting effect for theuneven illuminance which is substantially equivalent to that obtained bythe continuously changing transmittance distribution.

[0203] On the other hand, in the concentration filter plate 51D shown inFIG. 15C, a large number of light-shielding fine dot patterns composedof, for example, chromium, are deposited in the Y direction on asubstrate in a ratio of existence so that a predetermined transmittancedistribution (macroscopic concentration distribution) is obtained as awhole. Even when the concentration filter plate 51D is used, it ispossible to correct the uneven illuminance in the same manner as in thecase shown in FIG. 15A. The concentration filter plate 51D is alsoinstalled at the position slightly defocused from the conjugate planewith respect to the image plane. Because of the formation with a randomdistribution in partial areas respectively, the dot pattern is nottransferred onto the image plane. The random dot pattern is, forexample, a fine circular pattern having a diameter of about 25 μm.Assuming that the maximum correction amount for the centrally concaveunevenness is about 10%, the probability of existence of the dot patternat an arbitrary position in the concentration filter plate 51D ispostulated to be included within a range of about 0 to 15%.

Fourth Embodiment

[0204] Next, a forth embodiment of the present invention will beexplained with reference to FIGS. 16 and 17. In this embodiment, thecentro-symmetrical unevenness can be corrected even in a static exposurestate, not in a state after performing the scanning exposure. The basicarrangement of the projection exposure apparatus of this embodiment isthe same as that shown in FIG. 11. However, this embodiment differs inthat two concentration filter plates, which are rotatable respectively,are installed in place of the single concentration filter plate 51 shownin FIG. 11. In FIG. 16, components or parts corresponding to those shownin FIG. 12 are designated by the same reference numerals, detailedexplanation of which will be omitted.

[0205]FIG. 16 shows a relationship between the slit-shaped illuminationarea 35 and the optical system ranging from the fly's eye lens 9 to thefixed blind 14A of the projection exposure apparatus of this embodiment.In FIG. 16, a first concentration filter plate 51A and a secondconcentration filter plate 51B are adjacently arranged rotatably aboutthe optical axis IAX at the position slightly defocused toward thesecond lens system 13 from the plane slightly defocused from thearrangement plane of the fixed blind 14A, i.e., the conjugate plane withrespect to the reticle plane (conjugate plane with respect to the imageplane). One-dimensional transmittance distribution, which has the samecharacteristic as that of the concentration filter plate 51 shown inFIG. 11 and which is axially symmetrical in relation to the opticalaxis, is formed on each of the two concentration filter plates 51A, 51B.

[0206] The concentration filter plate 51A is driven and rotated by anangle θA within a range of 90° counterclockwise about the center of theoptical axis IAX by the aid of a driving section 52WA and a gear section52GA installed to the periphery of the first concentration filter plate51A. On the other hand, the concentration filter plate 51B is driven androtated by an angle θB within a range of 90° clockwise about the centerof the optical axis IAX by the aid of a driving section 52WB and a gearsection 52GB installed to the periphery of the second concentrationfilter plate 51B. Further, in the initial state of this embodiment, theangles of rotation of the two concentration filter plates 51A, 51B areset so that the average transmittance distribution in the non-scanningdirection is flat in the same manner as in the concentration filterplate 51 shown in FIG. 14A.

[0207] When the centro-symmetrical unevenness (especially the centrallyconcave unevenness) is corrected, the two concentration filter plates51A, 51B are driven by an identical angle of rotation in oppositephases, i.e., by an identical angle of rotation in opposite directions.Accordingly, the transmittance distribution can be corrected with anaxially symmetrical two-dimensional distribution about the center of theoptical axis IAX. Therefore, it is possible to obtain a uniformilluminance distribution over the entire surface of the illuminationarea 35 (and consequently the exposure area 35P) in the static state.Further, the uniformity of the σ value of the illumination opticalsystem is not deteriorated.

[0208]FIG. 17 shows a state in which the concentration filter plates51A, 51B are rotated in the opposite phases as described above. In FIG.17A, the concentration filter plate 51A is rotated counterclockwise by45° (θA=45°). In FIG. 17B, the concentration filter plate 51B is rotatedclockwise by 45° (θB=45°). In this case, the transmittance distributionsin the opening of the fixed blind 14A, which are brought about by theconcentration filter plates 51A, 51B, are those shown in FIGS. 17B and17D respectively. Actually, the transmittance distribution in theopening of the fixed blind 14A is concentric about the center of theoptical axis IAX as shown in FIG. 17E. That is, the bright and darkareas in FIGS. 17B and 17D are offset to one another. Thus, the idealcentrally symmetrical secondary transmittance distribution is obtainedin both of the X direction and Y direction without performing anyintegration in the scanning direction. When the ordinary centrallyconcave unevenness is corrected with this transmittance distribution,the uneven illuminance in the static exposure state can be alsocorrected simultaneously. The two-dimensional uneven illuminance asdescribed above can be measured with the sensor having the pinhole-shaped light-receiving section 42 a, of the uneven illuminancesensor 42 shown in FIG. 13A.

[0209] Upon the maintenance for the actual projection exposure apparatusof the scanning exposure type, a case also arises, in which the exposureis performed in a static state without performing the scanning.Therefore, the correction of the uneven illuminance in the static stateaccording to this embodiment is effective. The two concentration filterplates 51A, 51B of this embodiment are not limited to the use for thescanning exposure type exposure apparatus, which can be also adopted inorder to correct the uneven illuminance in the exposure apparatus of thefull field exposure type (static exposure type). That is, the presentinvention is also applicable to the exposure apparatus of the full fieldexposure type.

Fifth Embodiment

[0210] Next, a fifth embodiment of the present invention will beexplained with reference to FIGS. 12 and 18. In this embodiment, thepresent invention is applied to correct the inclination unevenness(linear function-like unevenness) in which the illuminance is graduallyincreased or decreased so that the optical axis is traversed in thenon-scanning direction. The inclination unevenness is not changed in atime-dependent manner by the cloudiness of the optical element of theillumination optical system or the like. It is unnecessary to provide anextremely wide correction range as well. However, the inclinationunevenness is an amount to be corrected, for example, upon the start-upafter the assembling and the adjustment of the projection exposureapparatus.

[0211] In the projection exposure apparatus shown in FIG. 11, theinclination unevenness is corrected by controlling the tilt angle of thesecond lens system 13. However, it is feared that the uniformity of theσ value of the illumination optical system is deteriorated during thisprocess. In order to avoid such an inconvenience, in this embodiment,the concentration filter plate 51 shown in Fig. 12 is exchanged with aconcentration filter plate 155 for correcting the inclinationunevenness. The concentration filter plate 155 for correcting theinclination unevenness may be arranged closely to the concentrationfilter plate 51 for correcting the centro-symmetrical unevenness. Arotary driving unit (52G, 52W) for the concentration filter plate 155for correcting the inclination unevenness has such a function that theconcentration filter plate 155 is rotated by an arbitrary angle θ withina range of ±90° (180° in range) about the center of the optical axisIAX.

[0212]FIG. 18A shows a positional relationship between the fixed blind14A and the concentration filter plate 155 for correcting theinclination unevenness in the initial state. In FIG. 18A, thetransmittance distribution T(X) of the disk-shaped concentration filterplate 155 is set to be a one-dimensional distribution which is graduallyincreased across the optical axis from the end in the −Y direction tothe end in the +Y direction. That is, the transmittance T(Y) of theconcentration filter plate 155 in the Y direction is represented by thefollowing expression with a coefficient b. The origin of the Ycoordinate is the optical axis, and R represents the radius of theconcentration filter plate 155.

T(Y)=b·Y+(1−b·R)  (5)

[0213] The maximum value of the transmittance is 1 (Y=R), and theminimum value is (1−2b·R) (Y=−R). The maximum correction amount is 2b·R.The inclination unevenness is not changed in a time-dependent mannerunlike the centro-symmetrical unevenness. It in enough to provide aslight correction amount. The coefficient b has an extremely smallvalue. Accordingly, when the filter plate is not rotated, theilluminance loss is kept within a slight ratio. Therefore, the averagetransmittance T(X) in the non-scanning direction shown in FIG. 18A isconstant at a value which is slightly lowered from 1 (100%) as shown bya straight line 156A. Actually, when the unevenness of the exposureamount in the non-scanning direction measured by using the unevenilluminance sensor 42 shown in FIG. 13 is the inclination unevenness,the inclination unevenness can be corrected by rotating theconcentration filter plate 155 so that the inclination unevenness isoffset.

[0214] In this embodiment, the maximum correction amount of theinclination unevenness is obtained in the case of θ=90°. FIG. 18C isillustrative of a case of θ=+90°. In this case, the transmittance T(X)in the non-scanning direction is represented by an expression in which Yis substituted with −X in the expression (5) as shown by a straight line156C (provided that the origin of the coordinate X is the optical axis).In this case, for example, if it is assumed that the inclinationunevenness may be generated in ±1% in maximum at the periphery withrespect to the position in the vicinity of the optical axis in theoptical system of this embodiment, the coefficient b may be set asfollows in order to correct the inclination unevenness.

b=0.98/(2·R)  (6)

Sixth Embodiment

[0215] Next, a sixth embodiment of the present invention will beexplained with reference to FIGS. 19 and 20. In this embodiment, thecentro-symmetrical unevenness in the static exposure state is correctedwithout badly affecting the uniformity of the σ value of theillumination optical system by using one concentration filter plate.Also in this embodiment, the projection exposure apparatus shown inFIGS. 11 and 12 is basically used. However, this embodiment differs inthat a rotatable concentration filter plate, which has a substantiallyconcentric transmittance distribution, is used in place of theconcentration filter plate 51 shown in FIG. 12.

[0216]FIG. 19A shows the rotatable concentration filter plate 161 forcorrecting the centrally concave unevenness to be used in thisembodiment. In FIG. 19A, the concentration filter plate 161 is formed bydeposing a light-shielding substance or a dimming substance with apredetermined substantially concentric transmittance distribution T(r)on a first surface of a light-transmissive circular thin substrate. Thecenter of the concentration filter plate 161 is coincident with theoptical axis of the illumination optical system. Explanation will bemade assuming that the y axis extends in the direction corresponding tothe scanning direction passing through the optical axis, and the x axisextends in the direction corresponding to the non-scanning direction.

[0217] In order to explain the transmittance distribution in thisembodiment, the transmittance T (r, φ) represented by the polarcoordinate is expressed as follows by substituting the coefficient awith a function a(φ) of the angle φ and substituting the position Y withthe radius r, in the transmittance T(Y) in the expression (2C). Thecoefficient a(φ) is represented as follows assuming that the maximumcorrection amount D in the expression (2B) is the function D(φ) of theangle φ.

T(r,φ)=1/{a(φ)·r ²+1}  (11)

a(φ)=D(φ)/{(1−D(φ))R ²}  (12)

[0218] In this case, the polar coordinate system (φ, r) can be convertedinto the rectangular coordinate system (x, y) by using the followingexpressions of relations.

φ=tan⁻¹(y/x)  (13)

r=(x ² +y ²)^(1/2)  (14)

[0219] Accordingly, the expression (11) is expressed by the rectangularcoordinate system (x, y) as follows by using the expressions ofrelations.

T(x,y)=1/{a(x,y)·(x ² +y ²)+1}  (15)

[0220] If the coefficient a is determined assuming that “the angularvelocity is constant” for the change of the transmittance, a(φ) in theexpression (12) is represented as follows.

a(φ)=φ·D/{(π/2−φ·D)R ²}  (16)

[0221] The transmittance T(x, y, θ) in the rectangular coordinate system(x, y), which is obtained after rotating the concentration filter plate161 shown in FIG. 19A by the angle θ, is represented as follows.$\begin{matrix}{{T\left( {x,y,\theta} \right)} = \frac{1}{\left\lbrack {{\left\{ \frac{\tan^{- 1}{{\frac{{y\quad \cos \quad \theta} + {x\quad \sin \quad \theta}}{{x\quad \cos \quad \theta} - {y\quad \sin \quad \theta}}} \cdot D}}{\frac{\pi}{2} - {\tan^{- 1}{{\frac{{y\quad \cos \quad \theta} + {x\quad \sin \quad \theta}}{{x\quad \cos \quad \theta} - {y\quad \sin \quad \theta}}} \cdot D}}} \right\} \cdot \left\{ \frac{x^{2} + y^{2}}{R^{2}} \right\}} + 1} \right\rbrack}} & (17)\end{matrix}$

[0222] According to the expression (17), it is possible to determine thetransmittance at an arbitrary position (x, y) at an arbitrary angle ofrotation θ.

[0223] Specifically, FIG. 19B shows the value T of the transmittanceT(x, y, θ) at the position of the radius r in the non-scanning directionfrom the center (optical axis) when the angle of rotation θ (rad) is setto have three types. In FIG. 19B, a flat straight line 162A representsthe transmittance T obtained when the angle of rotation θ is 0. A curve162B represents the transmittance T obtained when the angle of rotationθ is π/4 (45°). A curve 162C represents the transmittance T obtainedwhen the angle of rotation θ is π/2 (90°). The following facts areappreciated. That is, as the angle of rotation θ approaches π/2, thetransmittance T at the peripheral portion decreases in a manner ofquadratic function of the radius r. When the angle of rotation θ is π/2,then the amount of decrease of the transmittance at the peripheralportion with respect to the central portion is the maximum correctionamount D, and the correction amount with respect to the centrallyconcave unevenness is maximum.

[0224] The concentration filter plate 161 described above is provided tocorrect the centrally concave unevenness. Similarly, it is also possibleto produce a concentration filter plate for correcting the unevenilluminance in which the illuminance is increased at the position in thevicinity of the optical axis in a manner of quadratic function(hereinafter referred to as “centrally convex unevenness”). For thispurpose, a transmittance distribution, in which the transmittancedistribution of the concentration filter plate 161 is inverted, may bepossessed. Further, it is also possible to produce a concentrationfilter plate capable of correcting both of the centrally concaveunevenness and the centrally convex unevenness by changing the angle ofrotation of one concentration filter plate.

[0225]FIG. 20A shows the concentration filter plate 63 which isrotatable and which is capable of correcting both of the centrallyconcave unevenness and the centrally convex unevenness. In FIG. 20A, thecenter of the concentration filter plate 63 is coincident with theoptical axis of the illumination optical system. Explanation will bemade assuming that the x axis and the y axis extend in the directionscorresponding to the non-scanning direction and the scanning directionpassing through the optical axis respectively.

[0226] Also for the concentration filter plate 63, it is assumed thatthe change of the correction amount of the centrally concave unevennessand the centrally convex unevenness at an arbitrary angle of rotation isproportional to the change of angle. It is assumed that M represents thecorrection amount for the centrally convex unevenness, and φ′ representsthe angle of rotation upon the change from the correction for thecentrally convex unevenness to the correction for the centrally concaveunevenness. On this assumption, the transmittance T(x, y, φ′) at thecoordinate (x, y) when the angle of rotation θ is φ′, and thetransmittance T(xmax, ymax, 0) in which the angle of rotation θ is 0 andthe coordinate (x, y) is the maximum value (value at the position mostseparated from the optical axis) (xmax, ymax) are as followsrespectively.

T(x,y,φ′)=1−M  (18A)

T(xmax,ymax, 0)=1  (18B)

[0227] When these expressions are used, the maximum correction amountD(φ), and the maximum correction amount D(x, y, θ) at the angle ofrotation θ are as follows. $\begin{matrix}{{\begin{matrix}\begin{matrix}{Maximum} \\{correction}\end{matrix} \\{amount}\end{matrix}{D(\varphi)}} = {\frac{M}{1 - {2M}}\left( {\frac{\varphi}{\varphi^{\prime}} - 1} \right)}} & (19) \\{{D\left( {x,y,\theta} \right)} = {\frac{M}{1 - {2M}}\left( {{\frac{1}{\varphi^{\prime}}\left\lbrack {\tan^{- 1}{\frac{{y\quad \cos \quad \theta} + {x\quad \sin \quad \theta}}{{x\quad \cos \quad \theta} - {y\quad \sin \quad \theta}}}} \right\rbrack} - 1} \right)}} & (20)\end{matrix}$

[0228] When the maximum correction amount D(x, y, θ) is used, thetransmittance T(x, y, θ) at the angle of rotation θ in the expression(17) is as follows. $\begin{matrix}{{T\left( {x,y,\theta} \right)} = \frac{1}{{\left\lbrack \frac{D\left( {x,y,\theta} \right)}{\left( {1 - {D\left( {x,y,\theta} \right)}} \right)\quad \bullet \quad R^{2}} \right\rbrack \left( {x^{2} + y^{2}} \right)} + \left( \frac{1}{1 - M} \right)}} & (21)\end{matrix}$

[0229] According to the expression (21), it is possible to determine thetransmittance at an arbitrary position (x, y) at an arbitrary angle ofrotation θ.

[0230] Specifically, FIG. 20B shows the value T(r) of the transmittanceT(x, y, θ) at the position of the radius r in the non-scanning directionfrom the center (optical axis) when the angle of rotation θ (rad) is setto have three types. In FIG. 20B, an upwardly directed curve 64Arepresents the transmittance T obtained when the angle of rotation θ is0. A flat straight line 64B represents the transmittance T obtained whenthe angle of rotation θ is φ′ (0<φ′<π/2). A downwardly directed curve64C represents the transmittance T obtained when the angle of rotation θis π/2 (90°). It is understood that in the range in which the angle ofrotation θ is smaller than φ′, the transmittance T is increased in amanner of quadratic function of the radius r, and thus it is possible tocorrect the centrally convex unevenness, while in the range in which theangle of rotation θ is larger than φ′, the transmittance T is decreasedin a manner of quadratic function of the radius r, and thus it ispossible to correct the centrally concave unevenness. Further, when theangle of rotation θ is 0, then the amount of increase of thetransmittance at the peripheral portion with respect to the centralportion is the maximum correction amount M, and the correction amountfor the centrally convex unevenness is maximum. When the angle ofrotation θ is π/2, the correction amount for the centrally concaveunevenness is the maximum correction amount D represented by thefollowing expression. $\begin{matrix}{D = {\frac{M}{1 - {2M}}\left( {{\frac{1}{\varphi^{\prime}} \cdot \frac{\pi}{2}} - 1} \right)}} & (22)\end{matrix}$

[0231] In the concentration filter plates 161, 63 shown in FIGS. 19 and20 of this embodiment, the transmittance distribution is optimizedtwo-dimensionally. Therefore, they are not limited to the use for theprojection exposure apparatus of the scanning exposure type. They can bealso used for the projection exposure apparatus of the full fieldexposure type.

[0232] In the embodiment described above, for example, the concentrationfilter plates 51, 161, 63 are used as the filter. In place thereof, forexample, a transmission type liquid crystal panel, in which the internalpattern is controllable, may be used, and the internal pattern(transmittance distribution) may be electrically controlled. In theembodiment described above, the adjustment is performed during themeasurement of the illumination characteristic (at least one of theillumination telecentricity and the uneven illuminance (exposure amountunevenness)). Alternatively, the illumination characteristic may beadjusted during a period other than the period of the measurement. Forexample, the change of the illumination characteristic may be calculated(for example, by means of simulation), and the illuminationcharacteristic may be successively adjusted on the basis of the resultof the calculation. Alternatively, the illumination characteristic maybe periodically measured to perform the adjustment, and the illuminationcharacteristic may be adjusted by means of the calculation as describedabove during the period of the periodic measurement. As for the unevenilluminance (exposure amount unevenness), both of the inclinationunevenness and the centro-symmetrical unevenness (concave/convexunevenness) may be adjusted upon the change of the illuminationcondition, i.e., the intensity distribution (especially its shape) ofthe exposure light beam IL on the pupil plane of the illuminationoptical system. Only the centro-symmetrical unevenness may be adjusteduntil the change of the illumination condition next time.

[0233] In the embodiment described above, the illuminationcondition-switching system includes all of the aperture diaphragm plate10, the optical integrator (first fly's eye lens) 6, the light amountdistribution-converting element (diffractive optical element) 55, andthe switching unit 56. However, the illumination condition-switchingsystem may include only the aperture diaphragm plate 10 or only theswitching unit 56. The switching unit 56 may perform only the exchangeof the plurality of light amount distribution-converting elementsdescribed above. Further, for example, at least one of a zoom opticalsystem and a pair of prisms (conical prism (axicon) or quadrangularpyramid prism) relatively movable in the direction of the optical axisof the illumination optical system may be arranged between the exposurelight source 1 and the optical integrator (second fly's eye lens) 9, incombination of at least one of the aperture diaphragm plate 10 and theswitching unit 56, or in place of the aperture diaphragm plate 10 andthe switching unit 56.

[0234] In the embodiment described above, the fly's eye lens 6, 9 isused as the optical integrator. However, it is clear that the presentinvention is also applicable when an inner surface reflection typeintegrator (rod integrator) is used as the optical integrator. Further,in the embodiment described above, the illumination optical system ILSbased on the so-called double-fly's eye system, in which the two-stagefly's eye lens system 6, 9 is employed, is used. However, the presentinvention is also applicable when the illumination optical system isadjusted by using only the one-stage optical integrator (for example,fly's eye lens and rod integrator). Further, the diffractive opticalelement (DOE) may be used as the optical integrator not only for themodified illumination but also, for example, for the ordinaryillumination and the small a value illumination. Of course, in thiscase, it is desirable that a plurality of diffractive optical elementsare prepared to exchange them depending on the illumination condition.For example, when the inner surface reflection type integrator, in whichthe light-incoming plane is arranged at the pupil plane of theillumination optical system and the light-outgoing plane is arranged inconjugation with the pattern plane of the reticle 28, is used as theoptical integrator 9, and the optical unit, which includes at least oneof the plurality of light amount distribution-converting elements(diffractive optical elements), the zoom optical system, and the pair ofprisms described above, is arranged between the exposure light source 1and the optical integrator 9, then the incident angle range of theexposure light beam IL coming into the inner surface reflection typeintegrator is changed upon the change of the illumination condition.When the fly's eye lens is used as the optical integrator 9, a surfacelight source composed of a plurality of light source images, i.e., asecondary light source is formed on the side of the light-outgoingplane. When the inner surface reflection type integrator is used, asecondary light source composed of a plurality of virtual images isformed on the side of the light-incoming plane. Therefore, the change ofthe illumination condition in each of the embodiments described above isequivalent to the change of the intensity distribution of the exposurelight beam IL on the pupil plane of the illumination optical system, andthe change of at least one of the size and the shape of the secondarylight source formed on the pupil plane of the illumination opticalsystem.

[0235] In the embodiment described above, the present invention isapplied to the projection exposure apparatus based on the scanningexposure system. However, the present invention is also applicable tothe projection exposure apparatus (stepper) based on the step-and-repeatsystem (full field exposure system), and the exposure apparatus basedon, for example, the proximity system in which the projection system isnot used. The exposure light beam (exposure beam) is not limited to theultraviolet light as described above. For example, the EUV light beam inthe soft X-ray region (wavelength: 5 to 50 nm) generated from the SOR(Synchrotron Orbital Radiation) ring or the laser plasma light sourcemay be used. In the EUV exposure apparatus, each of the illuminationoptical system and the projection optical system is constructed by onlya plurality of reflection optical elements. In this case, theconcentration filter 51 may be composed of a reflecting member.

[0236] A semiconductor device can be produced from the wafer W shown inFIG. 1. The semiconductor device is produced by performing, for example,a step of designing the function and the performance of the device, astep of producing a reticle based on the foregoing step, a step ofmanufacturing the wafer from a silicon material, a step of exposing thewafer with a pattern on the reticle by using the projection exposureapparatus of the embodiment described above, a step of assembling thedevice (including a dicing step, a bonding step, and a packaging step),and an inspection step.

[0237] The way of use of the exposure apparatus is not limited to theexposure apparatus for producing the semiconductor element. The presentinvention is also widely applicable, for example, to the exposureapparatus for the liquid crystal display element formed on an angularglass plate or for the display device such as the plasma display, andthe exposure apparatus for producing various devices including, forexample, the image pickup element (for example, CCD), the micromachine,and the thin film magnetic head. Further, the present invention is alsoapplicable to the exposure step (exposure apparatus) to be used when themask (for example, photomask and reticle) formed with the mask patternof various devices is produced by using the photolithography step.

[0238] It should be understood that the present invention is not limitedto the embodiments described above, which includes a variety ofmodifications and improvements of the embodiments described aboveconceived by those skilled in the art within a range not deviated fromthe scope and the spirit of the present invention. For example, theshape of the concentration filter plate is not limited to the circularconfiguration, which may be an arbitrary configuration such as arectangular configuration. An arbitrary dimming material may be used asthe material for constructing the concentration filter plate. In orderto control the transmittance distribution, the concentration filterplate is not necessarily rotated in the plane. The concentration filterplate may be rotated or moved three-dimensionally. The embodimentdescribed above is illustrative of the case in which the filter of thepresent invention is provided in the vicinity of the plane conjugatewith the exposure plane of the wafer corresponding to the second object.However, there is no limitation thereto. The filter may be provided inthe vicinity of the exposure plane of the wafer corresponding to thesecond object, for example, in the space between the wafer and theprojection optical system. Further, with respect to reticles (mask), notonly a transmittal type of reticle through which an exposure light beamtransmits, but another reflective type of reticle on which the exposurelight beam is reflected may be used in this invention.

[0239] According to the present invention, the illumination system(illumination optical system) of the exposure apparatus can be adjustedcorrectly for a short period of time. When the characteristic-measuringsystem for measuring the illumination characteristic of the illuminationsystem is provided, the illumination system having a plurality ofillumination conditions can be adjusted automatically.

[0240] When the inclination component and the magnification component ofthe collapse amount of the telecentric property of the exposure lightbeam are measured in a divided manner as the illuminationcharacteristic, the adjustment can be correctly performed for a shortperiod of time by independently adjusting the both.

[0241] According to the present invention, the transmittancedistribution of the planer area or the flat plate-shaped filter iscontrolled. Accordingly, an advantage is obtained such that theuniformity of the exposure amount distribution can be improved withoutsubstantially deteriorating the uniformity of the coherence factor ofthe exposure light beam. The centro-symmetrical unevenness or theinclination unevenness can be corrected after the scanning exposure byusing the one filter which is rotatable and which has theone-dimensional transmittance distribution.

[0242] Further, various types of the centro-symmetrical unevenness canbe corrected even in the static exposure state by using the two filterhaving the one-dimensional transmittance distribution in combination, orby using the one filter having the concentric transmittancedistribution. Further, according to the method for producing the deviceof the present invention, the device can be produced with a high linewidth control accuracy by using the exposure method of the presentinvention.

What is claimed is:
 1. An exposure apparatus for exposing a secondobject with an exposure light beam via a first object, the exposureapparatus comprising: an illumination system which includes a pluralityof optical elements, at least two of which are movable, and whichilluminates the first object via the plurality of optical elements withthe exposure light beam; and an adjusting system which adjusts a stateof the movable optical elements in order to independently control atleast an inclination component and a magnification component of acollapse amount of a telecentric property of the exposure light beam ofillumination characteristic of the illumination system.